CA1220557A - Modulable apparatus and methods for the classification of indexed objects - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

The apparatus comprises a mechanical sorting system and a control computer. The sorting system com-prises N queues (Q1, Q2, Q3) and M stacks, M optionally being zero and N being equal to or greater than M. The computer comprises N memory areas (64Q1, 64Q2, 64Q3) organised in queue-like manner and M areas organised in stack-like manner. It also comprises a logic unit able to carry out sorting by index and/or sorting by desti-nation. Application to the classification or sorting of letters.

Description

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MODULABLE APPARATUS AND METHODS FOR THE CLASSIFICATION
_ ___ .
OF INDEXED OBJECTS.
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The present invention relates to a modulable apparatus for the classification of indexed objects and classification methods using said apparatus. It can be used whenever it is wished to classify objects according to the increasing or decreasing values of a code ~llocated thereto, whereby said code can express various criteria ~.g. a destination. A preferred field of application for the invention is the classification of letters or cheques.
A presently used process for bringing about the classification of objects consists of performing a cascade of successive sorting operations starting from the least significant digits of the numerical code used for the classification.
Each sorting operation consists of a separation of the batch to be classified into N
subassemblies, if the digit to which this sorting operation relates is liable to assume N values. When ; 20 the entire batch has been sorted according to this digit, the N subassemblies are stacked in the order of N values taken and the following sorting operation is then carried out for the immediately higher significance digits. The batch is classified when the successive sorting operations in accordance with all the digits have been performed.
This process involving successive sorting operations only offers a partly automatic solution to the classification problem. Thus, it requires numerous intermediate manipulations, which have to be carried out ..

5~;'7 in a strictly defined order, because the slightest transposition on taking up again the sorted batches, makes it necessary to start all the work from the beginni~g.
In addition, the second sorting operation can only start when all the objects of the batch to be classi~ied have undergone the first operation, which largely prevents any preparatory work when the arrival of the objects to be classified is staggered in time.
The object of the present invention is to obviate these disadvantages by on the one hand making it possible to eliminate repeated manipulation and classification of a manual nature of the content of the sorting compartments and by on the other hand making it possible to rapidly incorporate batches which have arrived after the already classified batches.
The sorting principle according to the invention is based on the decomposition or breaking down of the sequence of codes associated with the objects into monotonic sequences (defined relative to the natural order relationship of real numbers) with the same or a different orientation and on the merging by collation of several of the sequences into a single sequence. Each sequence is designated or identified by its final element, which is called the salient point.
For carrying out this sorting operation, the invention provides an apparatus essentially comprising a mechanical sorting system and an electronic control system.

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PS5'~' The former comprises storage means organised in the form of a queue or line, i.e. able to remove the objects in the order in which they were introduced and optionally storage means organised in the form o~ a stack, i.e. able to remove the objects in the opposite order from that in which they were introduced.
This first system also comprises means for transferring the objects between the dif~erent storage means. The electronic system essentially comprises a control computer provided with storage areas organised in the form of a queue and storage areas organised in the form of a stack, in which the codes allocated to each object are stored. A fourth storage area of the said computer makes it possible to dynamically st~re in~ormation indicating whether each of the objects stored in a previously defined queue, called the reception means constitutes a salient point of a sequence. This computer has means for controlling the transfer of codes from one storage area to another in order to classify the codes in a given order in one of them and for controlling the corresponding displace-ments of the objects carrying the codes. The objects are finally classified in a given order relative to said code iTl the reception means.
According to a preferred embodiment of the apparatus according to the invention, the mechanical sorting or classifying system only comprises storage means organised in the form of a queue. The series of codes associated with the objects is then decomposed into sequences of t~e same orientation, i.e. all increasing s 7907 c-sL
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or all decreasing.
According to a secondary feature, the mechanical sorting system only having storage means organised in the form of a queue, is structured in several stages, the head, heading or header sequences of several storage means of the same stage being merged with one another, the sequence obtained by merging being loaded into a storage means of another stage.
This architecture makes it possible to carry out transfers or mergers of sequences simultaneously at different stages, so that the objects can be more rapidly sorted than in a single stage system.
According to another embodiment of the apparatus according to the invention~ the mechanicaI
sorting system comprises a number M of storage means organised in the form of a stack and the same number of storage means organised in the form of a queue, the series of codes associated with the objects then being decomposed into alternately increasing and decreasing sequences.
According to another embodiment of the apparatus according to the invent~n, the mechanical sorting system comprises a number M of storage means organised in the form of a stack and a number M+l of storage means organised in the form of a queue.
The invention also relates to an apparatus able to carry out sorting by destination, incorporating a mechanical sorting system and an electron control system. The former comprises storage means organised in - s 7907 c-sL

the form of a queue, i.e. able to remove objects in the order in which they were introduced and means for transferring the objects between the different storage means. The electronic control system essentially comprises a control computer provided with storage areas organised in the form of a queue and used for storing the codes allocated to each object. This computer has means for controlling the transfer of the codes from one storage area to another, the reception storage area being a function of the value of a digit of the code, classification being carried out by successive sorting operations on each of the digits of the codes.
According to an advantageous embodiment of the apparatus according to the invention, the computer is able to carry out sorting by destination or sorting by indexing as a function of the productivity of the code read.
The features of the invention can best be gathered from the following description of an embodirnent given in an explanatory and non-limitative rnanner and with reference to the attached drawings, wherein show:
Fig 1 a block diagram of an embodiment of the apparatus according to the invention, in which the mechanical sorting system only has storage means organised in the form of a queue.
Figs 2a and 2b diagrams illustrating two methods for managing the transfer of sequences of objects from one storage means to another.

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Fig 3 a diagram illustrating a first operating mode of the apparatus of Fig 1.
Fig 4 a diagram illustrating a second operating mode of the apparatus of Fig 1.
Fig 5 a diagram illustrating a third operating mode of the apparatus of Fig 1.
Fig 6 a block diagram of an embodiment of the mechanical classification system only having storage means in the form of a queue and which are grouped in two stages.
Fig 7 a block diagram of a variant of an embodiment of the mechanical classification system incorporating queue-type storage means grouped in three stages and permitting processing of the objects as a function of their productivity.
Fig 8 a block diagram of an embodiment of the mechanical classification system of an apparatus according to the invention with three storage means organised in the form of a queue and two storage means organised in the form of a stack.
Fig 9 a block diagram of an embodiment of the mechanical classification system of an apparatus according to the invention with three storage means organised in the form of a queue and three storage means organised in the form of a stack.
It is firstly appropriate to define what is meant by sequence and salient point. As stated hereinbefore, it is possible to decompose the series of codes of the objects to be classified into a single type of sequence (sequences of the same orientation) or into two types of ~Z~5~7 sequence ~consecutive sequences of different orientations). This decomposition is linked with the storage means of the mechanical classification system If the latter only has storage mean6 organised in the form of a queue, the order of the code is decomposed into a single type of sequence. If this comprises storage means organised in the form of stacks and storage means organised in the form of a queue, the series of codes is decomposed into two types of sequence.
For example, the decomposition into sequences of the same orientation of the following series will be indicated:
576,8049640,300,186,339,199,905,407,139,94,919,858, 419,127.
The decomposition into increasing sequences is as follows:
576,80~/ ~ / ~ /186,39~9 ~ ~ / ~ /
419/127.
The decomposition into decreasing sequences is as follows:
-576/~04,640,300,186/3~9,199/9-05,407,1g3,94/919,898, 419,127.
In these representations, the arrows indicate the orientation of the sequences and the oblique delimit the sequences. The final element of a sequence is called the salient point. The sorting operation can be represented as an operation of eliminating salient points (the last element of the last i -'5' ~ B 7907 C-BL

~ZQS~ 7 sequence not being considered as a salient point~
It is pointed out that the two decompositions are not equivalent, one having 11 sequences and the other only 5. As can be gathered from the rest ~ the description, all things being equal, the smaller the number of sequences, the faster the sorting. For optimum sorting, the control computer of the electronic processing system will consequently store the series of salient points corresponding to the shortest decomposition into a number of sequences.
Fig 1 shows an apparatus according to the invention, whose three storage means are organised in the form of a queue. This apparatus essentially has two parts, a mechanical sorting system 10 and an electronic control system 20. The mechanical sorting system 10 comprises:
A) a first means Ql for the storage of objects organised in the form of a queue, i.e. able to remove the objects in the order in which they were introduced, said means being consequently provided with an element Qil for introducing the object into the queue and an element Qel for extracting the first object from the queue;
B) a second means Q2 for the storage of objects organised in the form of a queue and provided with an introduction element Qi2 and an extraction element Qe2;
C) a third means Q3 for the storage of objects organised in the form of a queue and provided with an introduction element Qi3 and an extraction element Qe3;
D) a means for transporting or transferring the objects to be classified incorporating a certain number of ~22~5~

branches and branching points; an introduction branch 30 between an inlet 32 and the introduction element Qil of the first storage means ~19 a branch 34 between extraction element Qel of said first means and the introduction element Qi2 of the second storage means Q27 said branch having a first switch point A, a branch 36 between switch point A and introduction element Qi3 of the third s~orage means Q3, said branch having a second switch point B , a branch 38 connecting the second switch point B to introduction branch 30, a branch 40 connecting extraction element Qe3 of the third storage means Q3 to said same introduction branch and a branch 42 connecting extraction element Qe2 of the second storage element Q2 to said same introduction branch.
The electronic control system 20 comprises:
means 50 for reading a numerical code on the objects passing along the introduction branch 30 and a control computer 60 incorporating:
a) a buffer input circuit 62 connected to reading means 50;
b) a memory 64 able to receive the codes of the different objects introduced into the sorting system, said memory comprising three areas 64Ql, 64Q2 and 64Q3 operating in queue-like manner according to the FIF0 or "First-in-first out" procedure, a fourth memory area 64I in whichis stored the information indicating for each of the codes of area 64Ql whether said code constitutes a salient point and finally a fifth memory area 64T
comprising instructions; the stored codes being classified in the three storage areas 64Ql, 64Q2, 64Q3 ., ~Z2~S~'~

-in the same way as the processed or treated objects are respectively classified in means Ql' Q2 and Q3;
c) a circuit 66 for reading the data and instructions stored in memory 64, d) a logic unit 68 carrying out the programme instructions for processing data and classification in the memory;
e) a buffer outpu~ circuit 69 connected to logic unit 68 and having 8 outputs respectively connected to the object introduction element Qil, Qi2, Qi3, two extraction elements Qel, Qe2, Qe3 and to the two switch points A
and B, said circuit supplying control signals able to control the elements in question.
Thus, the operation of sorting the objects to be classified consists of two types of operation:
sequence merging operations and sequence transfer operations.
Sequence merging operations relate to sequences of objects positioned at the head of the storage means of the mechanical classification or sorting system. As a function of the operating mode of the apparatus, defined by the instructions stored in area 64T, the merged sequences come from each of the storage means or from certain of said storage means only. These different operating modes are illustrated by the different apparatuses described in the remainder of the text.
The sequence transfer operations consist of moving one or more sequences of the reception means towards another storage means. The number of object sequences transferred from the reception means to each s 7907 c-sL

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storage means during each iteration of the sorting algorithm is of a random nature. A first possible transfer mode consists of transferring, during each iteration of the sorting algorithm, a single sequence from the rec~ption means into each of the storage rneans.
Another possibility consists of distributing in a single transfer operation, the sequencesof objects contained in the reception means into each of the storage means. Between these two extreme object sequence transfer modes, there can obviously be transfer modes in which, for each iteration, some sequences of the reception means are transferred into each of the storage means. I
Figs 2a and 2b respectively illustrate the case where each storage means receives, during each iteration, a single sequence from the reception means .
and the case where all the sequences of the reception means are distributed, in a single transfer operation, between all the storage means.
In Fig 2a, a mechanical sorting system of an apparatus according to the invention is symbolized by three storage means organised in the form of a queue and designated respectively Ql' Q2' Q3 Each o storage means comprises an introduction element respectively designated Qil, Qi2 and Qi3 and an extraction element respectively designated Qel, Qe2 and Qe3.
Initially~ the reception means Ql contains four monotonic sequences, each of which is symbolized by an arrow and a digit, the latter indicating the order t B 7907 c-sL
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~lZZl' Si~' number of the sequence in the storage means Ql Following the first transfer operation Tl, the queue Q2 contains the sequence numbered 1 and queue~3 the sequence numbered 2. The following sorting algorithm operation consists of merging, by collating these two sequences. This operation is designated Fl. The sequence resulting from this merger 1-2 is deposited in queue Ql Thus 9 the double transfered - merger operation has reduced by one unit the number of sequences contained in queue Ql By iterating this double operation, the number of sequences in queue Ql will be decreased until there is only a single sequence. The classification is then ended.
The second transfer operation T2 transfers the sequence numbered 3 into queue Q~ and the sequence numbered 4 into queue Q3. These sequences are merged by collation by the merging operation F2, the resulting sequence 3-4 being deposited in queue Ql The third transfer operation T3 transfers the header sequence of Ql and designated 1-2 into queue Q2 and sequence 3-4 into queue Q3. The merging operation F3 brings about a merger by collating these two sequences and deposits the resultant sequence in queue Ql This resultant sequence is designated 1-2-3-4. As queue Q
only has a singl~ sequence, classification is ended.
It is possible to envisage an operating mode of the apparatus which slightly differs from that described. Thus, after each transfer operation, e.g. Tl, it is possible to merge the header sequences B 7907. C-BL

~z~ 7 of all the storage means, including reception means Ql Thus, each double transfer-merger operation reduces by two units the number of sequences of queue Ql- The classification of the series of objects contained in Ql then requires less stages than in the case described in Fig 2a.
Fig 2b illustrates another sequence transfer mode from the reception means into each of the storage means. In the latter, the sequences lnitially ~ntained in queue Ql are distributed~ in a single transfer operation, into the other queues Q2 and Q3.
Initially, queue Ql constituting the reception means contains four monotonic sequences, each symbolized by a n arrow and a digit indicating the number of said sequence. Following the first transfer operation Tl, queue Q2 contains the first two sequences numbered l and 2 of queue Ql and queue Q3 contains the last two sequences numbered 3 and~4 of queue Ql-The following operation of the sorting algorithm is a merging operation designated Fl. This operation consists of merging, by collation, o the two sequences of the same rank contained in queues Q2 and Q3. The sequences obtained and designated respectively l-3 and 2-4 are deposited in queue Ql This double transfer - merger operation is iterated. In the case represented in Fig 2b, queue Ql only contains two sequences, so each of the queues Q2 and Q3 receives a single sequence. More generally, each queue Q2 or Q3 receives half the sequences contained in Ql-B 7gO7 C-BL
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5~7 In the case of a system with three queues and if the number of se~uences is uneven, the last sequence can, for example, be kept in queue Ql As in the case of Fig 2a, it is possible to envisage a transfer mode differing slightly from that described with reference to Fig 2a by distributing, for each transfer operation, the sequences contained in queue Ql into each of the queues Ql' Q2 and Q3.
By merging on each occasion the sequences at the head of each of the three queues Ql' Q2 and Q3, the sequence number is reduced by two units at each merger.
The transfer and merger operations can be combined in different ways, which defines the same number of operating modes of the apparatus according to the invention. Three special modes will now be described with reference to Figs 3, 4 and 5.
The first operating mode consists of sequential transfer and merging operations, this constituting the simplest mode. In the second operating mode, the transfer operation partly takes place during the merging operation. This "masked time" operation reduces the overall object classification time. Finally, in the third operating mode, the sequences obtained by merging are successively deposited in each queue.
This leads to a reduction of the number of transfer operations.
For the better understanding of each of these operating modes, a description will now be given of the classification of the series referred to hereinbefore for each of these operating modes. It is ,~

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5~7 pointed out that when faced with the alternative increasing sequences - decreasing sequences, the apparatus will choose the decomposition having the smallest number of sequences and which, in this particular case, corresponds to a decomposition into decreasing sequences.
Reference is made to the series:
576,804,640,300,186,339,199,905,407,139,94,919,858, 419,1279 and its decomposition into decreasing sequences:
c . . - ~
~ /804,640,300,186/339,199/905,407,139,94/919,858, -419,127.
The mechanical classification system shown in Fig 3 is functionally identical to that shown in Fig 1. Branch 38 of Fig 1 is merely replaced by branch ~4 directly connecting extraction element Qel of queue Ql to introduction element Qil of the same queue. The controls performed during each operation and the state of the queues Ql' Q2~ Q3 is indicated-Ql (initial): 576/gO4,640,300,186/339,199/905, 407,139,94/919,858,~19,127 control: transfer of one sequence into Q2 and Q3, Ql ; 339,199/905,407,139,94/919,858,419,127 Q2 : 576 Q3 : 80~,640,300,186 control: merging the sequences at the head of Ql' Q2' Q3 Ql 905,407,139,94/919,858,419,127/804,640,576,339, 300,199,186 control: transfer of one sequence into Q2 and Q3 s 7907 c-sL
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Ql : 804,640,576,339,300,199,186 Q2 905~07,139,94 Q3 : 919,858,419,127 control : merging the sequences at the head of Ql' Q2 and Q3-Queue Ql then contains the series ofcorrectly classified codes and classification is ended.
The mechanical system of Fig 4 differs from that of Fig 3 in that the branch 44 directly connecting the extraction element Qel of queue Ql to its introduction Qil is eliminated. The sequence at the head of queue Ql can consequently no longer be merged with the sequences at the head of queues Q2 and Q3. Thus 9 the transfer of sequences from qu2ue Ql into queues Q2 and Q3 can take place at the same time as merging sequences of queues Q2 and Q3-Operation i~ as follows:Ql (initial): 576/804,640,300,186/339,195/905,407, 139,94/919,858,419,127 control: transfer of one sequence into Q2 and into Ql : 339,199/905,~07,139,94/919,858,~19,127 Q2 : 576 Q3 : 80~,640,300,186 control: merging the sequences at the head of Q2' Q3 and simultaneously transferring a sequence into Q~

Ql : 919~858~419~127/804~640~576g300~186 Q2 : 339,199 Q3 : 905,407,139,94.

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control : merg;ng the sequences at the head of Q2' Q3 and simultaneously transferring one sequence into Q2 and Q3 Ql : 905,~07,339,199,139 9 94 Q2 : 919~858,419,127 Q3 : 804,640,576,300,186 control: merging the sequences at the head of Q2 and Q3 and simultaneously transferring one sequence into Q2 and Q3 Ql :
Q2 : 905,407,339,19g,139~94 Q3 : 919,858,8045640,576,419,300,186,127 control : merging the sequences at the head of Q2 and Q3.
Queue Ql then contains the series of classified codes. In this operating mode, it would have been possible to distribute in a single operation all the sequences of Ql into Q2 and Q3.
The mechanical system shown in Fig 5 has a different architecture from the system shown in the two preceding drawings. In this case, each extraction element is connected to each introduction element.
In the preceding systems, the extraction elements were connected to the single introduction element of queue Ql Thus, any sequence resulting from a merger was received by queue Ql~ which transferred it during the following operation into another queue. The architecture of the system of Fig 5 eliminates this operation of temporary passage into Ql by making it possible to deposit a sequence obtained by merging directly in the queue where it will be subsequently merged.

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~lZ~5~7 This system operates as follows:
Ql (initial) : 576/804,6409300,186/339,199/905,407, 139,94/919,8589419,127 control : transfer of a third of the sequences, to within one or two~ into Q2 and Q3 Ql : 959 407,139,94/919,858,419,127 Q2 : 576/804, 640~ 300, 186 Q3 : 339,199 control : merging the sequences at the head of Ql~
Q2' Q3 and depositing in Ql Ql : 919,858,419,127/905, 576,~07 , 339,199, 139 , 94 Q2 : 804, 6409 300, 186 Q3 : -control : merging the sequences at the head of Ql and Q2 and depositing in Q2 Ql : 905,576,407,339,199,139,94 Q2 : 919,858,804,640,419,300,186,127 Q3 : -Control : merging the sequences at the head of Ql and Q2.
The sequence obtained is the series of classified codes and can be deposited in a random queue.
The Applicant has evaluated the total number -~ of object movements accord~ng to the three desrribed apparatus a~chitectures (~ representing the number of queues and ~ the number of objects);
system of Fig 3 : Ml .N.logM(2) system of Fig 4 : 2 N 1gM-1(2) system of Fig 5 : N.logM(N2 ).

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The performance levels are clearly better than ~hose of known classification apparatuses.
They can be further improved by ~reating a multistage mechanical sorting system architecture.
An example of such a system is shown in Fig 6 The first stage El is constituted by queues Qll' Ql2 and Ql3- The introduction elements Qill7 Qil2, Qil3 of each of these queues are connected to introduction branch 30 via switch points Al and A2 for queues ~ll and Ql~- The extraction elements of these queues are connected to a branch, the connection being ensured by branches 52 and 54 for queues Ql and Q2.
The second stage E2 is constituted by queues Q2l' Q22 and Q23. The introduction elements Qi2l, Qi22, and Qi23 are connected to branch 52, said connection taking place by switch points A4 and A5 for queues Q23 and Q22. In addition, extraction elements Qe2l, Qe22 and Qe23 of these queues are connected by branches 56, 58 and 60 to introduction branch 30. A
switch point A3 also makes it possible to connect branch 50 to a branch 62 connected to introduction branch 30.
This system comprises two three-queue stages.
The Applicant has calculated that the performance indicator of the system is logg(m), in which m is the number of sequences and is at the most equal to 2.
A system with six queues in parallel would only have one performance indicator of log6(m~. More generally, for a system of q.k queues, the performance indicator is logqk(m) for a system with k stages and logq k(m) for ~;2Z~5~

a system,with one stage.
The interest of a staged system is therefore obvious. Such a system is particularly useful for sorting the large volumes ~ objects, such as letters or cheques.
A simple operating mode for this system consists of storing the series of objects in one of the queues of the first stage, e-g- Qll' decomposing these series into sequences, distributing the sequences Q21' Q22 and Q23 of the second stage merging the sequences of the first rank of said queues, the sequences obtained by merging being successively transferred into queues Qll' Q12 and Q13 of the first stage, followed by the iteration of these merger -transfer operations from one stage to the other up tothe classification of the codes of the series.
In order to take full advantage of the architecture of the system, mergers can be simultaneously performed at different stages. In addition, in order to gain time at the start of processing, it is possible to choose a sequence orientation before loading the objects into the reception means. Instead of initially storing all the objects in Qll' it is then possible to distribute them from the outset, sequence by sequence, in all the queues of the first stage. Moreover, it is possible to start the merger - transfer operation of the sequences at the head of the queues at the first stage into the queues of the second stage as soon as each queue of the first stage contains a sequence and without waiting until all the objects are loaded into the system.

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The mechanical sorting systems ~f Figs 5 and 6 have been used for carrying out sorting by indexing of a series of codes. The architecture of ~he transfer means of these systems make them suitable for also carrying out sorting by destination, an adequate electronic control system being provided for controlling said mechanical sorting system.
The sorting by indexing described with reference to Figs 3 to 5 is a sorting operation adapted to the case where the number of different values of the codes of the series of objects to be classified is the order of magnitude of the number of elements of the series, i.e. when the codes are virtually all of a different value. However, in the opposite case where many of the codes have the same value and the number of different values is known, it is of greater interest to use another sorting procedure, i.e. sorting by destination.
A description will now be given of sorting by destination of a series of objects by means of an apparatus, whose mechanical sorting or classification system is the same as that of Fig 5.
The d (d~ 1) destinations of the objects to be sorted are designated by a number from 1 to d written into the base equal to the number of storage means of the mechanical sorting system. For example, if d=14, the mechanical sorting system having three storage means, the recoded destinations are:
000,001,002,010,011,012,020,021,022,100,101,110,111, 200.

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Sorting by destination consists of carrying out a cascade of different sorting operations, performed on the basis of the least significant operational digits of the recoded destination During each sorting operation, for each queue is transferred into queue Qi+1( ~ i ~2) the objects of said.queue whose digit of the processed rank is equal to i.
Operation can be clearly gathered from the fo~owing example. Consideration is to be given to the following series of objects to be classified:
110,01,00,10,02,01,111,12,21,20,100,00,12,11,101,01, 20,200,22,02,21,02,20,01,21, Control: entry of objects and depositing in queue Qi+1( ~i ~2) of the objects, whose least sign~ficant digit is equal to i.
Ql : 110,00,10,20,100,00,20,200,20 Q2 : 01,01,111,21,11,101,01,21,01,21 Q3 : 02,12,12,22,02,02 Control: for each queue, extract the objects fro~ said queue and deposit in queue Qi~1( ~ i ~ 2) the objects of said queue, whose second digit startingfrom the right is equal to i.
Ql 00,100,00,200/01,01,101,01,01/02,02,02 ~2 : 110,10/111,11/12,12 Q3 : 20,20,20/21,21,21/22 control : for each queue9 extract the object from said queue and deposit in queue Qi~1(~ i ~ 2) the objects of said queue, whose third digit starting from the right is equal to i.
30 Ql 00,00~1,01,01,01,02,02,02,10,11,12,12/20,20,20, z~r~

21,21,21,22 Q2 : 100,101/110,111 Q3 : 200 control : removal of the objects by stacking in order queues Ql' Q2 and Q3O
The series of objects is then classified.
One interest of the sorting process is that the number of "turns" of the classification loops is not dependent on the number of objects to be classified, but solely on the number of different destinations.
The Applicant has evaluated the classification speed (processing time). This speed is proportional to the performance indicator equal to logq(d), in which q is the number of queues and d the number of destinations.
When there is a single stage mechanical classification system, it is necessary to wait until all the objects ha~e arrived in the destinatory queues to start the following turn (then each queue is successively destacked). Destacking can only take place when all the objects have been introduced. It is clear that by using a mechanical sorting system with at least two stages (as shown in Fig 6), it is possible to destack queue Qll of the first stage cont~ining the destinations designated by a code having a 0 as the digit of the unit in queues Q21' Q22 and Q23 of the second stage throughout the filling stage. Thus, there is a large masked time operation (average gain = to 1/3 of the filling time for stages with three queues).
Moreover, when the apparatus operates on the basis of destination sorting, it is important to increase 5~'~

the instantaneous processing capacity and minimize the risks of blockages (Qll empty~ Ql2 Q13 recoding the most productive destinations by least significant codes and in general terms recoding the series of classified destinations in decreasing order of importance of the traffic flows by increasing the significant codes. This is possible in the case of the postal service, because it has a large amount of statistical information on such questions.
As soon as the first stage of the mechanical sorting system is empty or in the case of destacking, a second batch of objects can be introduced in order to start the sorting procedure for the latter. More generally and as a result of simple conditions regarding the size of the batches of objects and the formats of the queues, a machine with k stages can sort k successive batches, which leads to optimum utilization because this takes place with full capacity. An interesting variant of this destination sorting method using the recoding referred to hereinbefore is described hereinafter and is applied in exemplified manner to the sorting of the series of the 25 aforementioned objects, namely:
110,01,00,10,02,01,111,12,21,20,100,00,12,11,101,01,20, 200,22,02,2~,02,20,01,21.
The mechanical sorting apparatus must have a number of stages equal to the number of sorting operations necessary for the classification of the destinations or sufficient queues per stage for an apparatus whose number of stages is fixed. In the latter case, this number of queues per stage is determined 4 _ 'B 7907 C-BL

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by the calculation of the renumbering base ~ the destinations which must be such that the successive sorting operations only require a single passage through the mechanical sorting apparatus~
Fig 7 shows a mechanical sorting apparatus for performing this sorting variant. This apparatus comprises three stages of in each case two queues, respectively queue Q12 and Q13' Q22 Q23 32 and Q33. There is also a reception queue Q. Each of these queues is provided with an introduction element and an extraction element.
This apparatus incorporates a means for ~he tr~nsportation or the transfer of the objects provided with an introduction branch 30 connected to the introduction element Qi for queue Q. This introduction branch i5 connected via switch point A7 to a branch 82, which is itself connected by switch point A8 to introduction elements Qil2 and Qil3 of queues Q12 and Q13 Branches 84 and 86 connect the extraction elements of these queues to branch 30. In the same way, switch point A9, Alo, All and A12 and branches 88, 90,92,94,96 and 98 connect the introduction and extraction elements of queues Q22' Q23' Q32 and Q33 to branch 30.
The configuration shown in Fig 7 is able to very rapidly extract the most productive destinations or those for which there are special work organisation constraints and which also have been recoded by l~ast significant codes. Moreover, a material economy is obtained, b~cause queues Qll~ Q21' Q31 have been deleted, each stage having one queue less than in the configuration s 7907 c-sL

~L~2~

shown in Fig 6.
Control; entry of object5 and deposition in queues Ql i+~ 2) of the objects, whose least significant digit is equal to i;
depositing in Q2 i~ 2) of objects, whereof the second digit starting from the right is i and theleast significant digit is zero;
finally, depositing in Q3 i+l(l6 i~ 2~ of the objects, whose most significant digit is i and the two other digits 0; discharge of objects coded ooo .
The situation of the machine at the end of filling is as follows:
Q12 : ~1,01,111,21,11,101,01,21,01,21 Q13 : 02,12512,22J02,02, 15 Q22 : 110,10.
Q23 : 20,20,20 Q32 : 100.
Q33 : 200.
Q (common reception container) : 00,00.
The destination coded 00 (the most productive) has already been extracted.
Control: successively extract the objects from eacl queue of the first stage and deposit in queues Q2 i+l(l~ i~ 2) the objects, whereof the second digit 25 starting from the right is i, in queues Q3 i+l(l~ i ~ 2) t the objects, whereof the first digit starting from the right is i and the second is 0 and finally remove from the appara-tus the objects~ whereof the second and third digits are equal to 0.
The situation after emptying the first stage is .i!,, .
s 7907 c-sL

as follows:
Q22 : llQ,lO/~ ,12,12/
Q23 : 20J20,20/21,21,21,2~/
Q32 : lO0/101/
Q33 : ~00/
a oo, oo/ol, ol~ 01701,02,02,02/
Two supplementary destinations have been extracted~
Control: successively extract the objects from each ~ueue of the second stage and deposit in queues Q3 i+l(l ~ i ~2) the ob~ects9 whereof the third digit starting from the right is i and remove from the apparatus the objects, whereof the third digit is equal to 0.
The situation after emptying the second stage is as follows:
Q32 : 1OO/lOl/
Q33 : 200 Q . 00,00/01,01,01,01,02,02,02/10,11,12,12,20~20,20, 21,21,21922/
control: remov~ the objects from the apparatus by destacking in order queues Q32 and Q33.
It shou~l be noted that the objects corresponding to the destinations sorted in the third stage are well classified at each staging point, which means that the stage corresponding to the storage means is equal to l.
The final staging point of a destination sorting operation only has an object receiving function. Thus, there i.s no need to have a third stage, because, in all stages, the classified objects are conditioned either by tying into bundles ~r by containerization which maintains the S~'~

classification. In this hypothesis, sorting on the most significant digit must be carried out directly in adequate receptacles. Thus, in the case of destination sorting, there is a possible "downstream integration" of the object reception system with the actual sorting apparatus. This can be generally applied to any apparatus classifying a number d of directions in a single passage and forms part of the invention.
The same mechanical system can be used, as a function of the instructions contained in the electronic control system, either for index sorting, or for destination sorting.
Thus, it is possi~le to design a system having a computer using destination sorting for that part of the post or ~il corresponding to the most productive destinations3 as well as the least numerous destinations and the process of merging monotorlic sequences for very numerous and less productive destinations.
Two further improvements are possible. One relates to a better processing UpStrRam of the sorting operation (phase of loading the objects into the apparatus) whilst the other relates to better processing downstream of the sorting operation (phase of emptying the objects from the apparatus).
The interchangeable character of the monotonic sequences makes it possible to envisage without involving technical difficulties with respect to the apparatus controlled by the index sorting method, the possibility of accelerated fiIing of a machine with queues, which may or may not be arranged in stages.

;ts~l~

~9 Thus, it is possible to use a~ leas~ the same numberof injectors as there are queues and consequently to increase the flow on filling by a factor equal to their number. Correlatively, the filling phase time is divided by this number, which makes it possi~le to start the iterative collating phase after a very brief delay. However, the asynchronous character of the entrance and removal members of each of these queues may mean that this advantage is of far less interest.
However, if it is assumed that the reading means (50 ;n Fig 1) associated with each injector is positioned upstream of the injection member in the collating device, it is then possible to considerably reduce the number of sequences injected into the sorting machine. The performance indicator associated with a configuration of q queues and q reading means is:
logq(m/q)- logq(m)-1 The number of turnsof the collating loop is reduced by one unit and there is a very significant time gain.
For a machine with k stages of q queues provided with q reading means, the indicator is:
lg(qk)(m/q)= log( k)(m)-l/k This gain corresponds to an elimination of a transfer of all the objects to be classified from one stage to the other. Bearing in mind that the configuration of the apparatus must be adapted to the s 7907 c-sL

volume of traffic of the objects, this ~an lead to a significant time saving, which increases as k decreases. There is then a complete integration of the line of injectors into the actual sorting subsystem and a more intense and consequently effective use in this connection.
An accelerating device can also be envisaged for the apparatus controlled in destination sorting, but on this occasion at the time of emptying. Thus, during the final stage of the destination classification, the queues of the apparatus (with or without stages) are successively emptied in aclearly defined order.
Under these conditions, it is merely necessary to directly and simultaneously empty each of these queues into an associated container by separate conveying paths~ because this operation maintains the structure I
with the order resulting from the sorting operation.
The time saving is significant. However, this procedure raises the question of the use~ulness of transferring the objects into the stage corresponding to the sorting with respect to the most significant digit. This final sorting can directly take pl~ce in the reception containers9 the final stage or the last turn of the collating loop being eliminated as a function of the architecture of the machine used.
There is then also an integration of the object reception system and the actual classification device by close linking of the functions of each of them.
Thus, a machine with queues can be integrated without any particular technical problems into the sorting ~ . .

lZ~.'S~

operation chain upstream by a better use of the line of reading means for index sorting and downstream by a close linking of the object sorting and storage functions. This integration leads to significant time S savings and to a better cost/efficiency ratio.
H;therto, various architectures of the apparatus according to the invention have been described in which the mechanical sorting system only comprises storage means organised in the form of queues.
The possible operating modes of sa;d apparatuses have also been described. However, the invent~n is not limited to apparatuses, whose mechanical sorting system only comprises queues. On considering a decomposition of the series of codes of the objects into alternately increasing and decreasing sequences, it is possible to classify the series by having a mechanical sorting system which also has storage means organised in the form of stacks.
Examples of such mechanical sorting systems are diagrammatically shown in Figs 8 and 9. In Fig 8 J
the mechanical sorting system comprises two storage means organised in the form of stacks and three storage means organised in the form of queues. This is the general architecture for systems with M means organised in stacks and M+l means organised in queues. In Fig 9 the mechanical sorting system comprises three storage means organised in stacks and three storage means organised in queues. In general, a mechanical sorting system based on this architecture has the same number of stack storage means as there are queue storage means.

? S~7 3~
In order to explain the operation of the mechanical sorting or classifying system shown in Figs 8 and 9, for each of them the classification of the aforementioned series will be described:
576,804,640,300,186,339,199,905,407,139,94,919,898,419,127.
Two decompositions into alternate sequences are possible, depending on whether one starts with an increasing sequence or a decreasing sequence. For example, decomposition with an initial increasing sequence will be chosen and this leads to the following decomposition or breakdown:
5i6,8-0~/6~0,300,-1-86/3 ~ 1~ /9 ~/4 ~139,-94/9 ~ /8~8,419,127.
The increasing and decreasing sequences alternate and are designated by an arrow pointing to the right for an increasing series and pointing to the left for a decreasing series. On the present example, there are eight sequences.
The mechanical sorting system shown in Fig 8 comprises three storage means organised in queues Ql' Q2 and Q3 and two storage means organised in stacks Pl and P2. Each queue Ql~ Q2 and Q3 comprises an introduction elernent Qil, Qi2, Qi3 and an extraction element Qel, Qe2, Qe3. Stacks Pl and P2 are ~ch provided with an introduction element Pi1, Pi2 and an extraction element Pel and Pe2.
The mechanical sorting ~ystem also comprises means for transferring or transporting the objects to be classified and consisting of a cert~in number of branches and branching points: an introduction brarch 30 '_ B 7907 C-BL

receives at the entrance the objects to be classified and connected at the exit to the introduction element Qil of queue Ql' a branch 64 between extraction element Qel and queue Ql and introduction element Pil of stack S Pl, said branch having a first switch point Bl, a branch 66 between extraction element Pel of stack Pl and introduction element Qi2 of queue Q2' said branch having a switch point g2, a branch 68 between switch pointsBl and B2, a branch 70 between switch point B2 and introduction element Pi2 of stack P2, said branch having a switch point B3, a branch 72 between extraction element Pe2 of stack P2 and introduction element Qi3 of queue Q3, said branch having a switch point B4, a branch 74 between switch points B3 and B4, a branch 76 between switch point B4 and introduct;on branch 30, a branch 78 connecting extraction element Qe3 of queue Q3 to said same introduction branch and a branch 80 connecting extraction element Qe2 of queue Q2 to said same introduction branch.
The various stages of a classification process for the aforementioned scries adapted to the mechanical sorting system shown in Fig 8 are indicated hereinafter.
The controls performed are given for each new operation, as well as the successive states of queues Ql, Q2 and Q3 and stacks Pl and P2:
Ql (initial) 576,804/640,300,186/339/199/905,407, 139,94/919/898,~19,127.
control : transfer of one sequence into storage means 1' Q2' P2 and Q3-^ ~ s 7907 c-sL

Ql : 905/407,139,94/91~/898,~19,127.
Pl : 804,576.
Q2 : 640,3oo~186.
P2: 339 Q3 : 199.
Control : merging the sequences of the head of the storage means Q~, Pl, Q2' P2' Q3 Ql : 407,139,94/919/898,419 9 1~7/186,199,300,339,576, 640,804,905.
control: transfer of one sequence into each of the storage means Pl, Q2' P2~ Q3 Ql P2 : 94,139,407.
Q2 : 919 P2 : 127,419,898.
Q3 : 186,199,300,339,576,640,804,905.
control: merging the sequences at the head of the storage m~anS Ql' Pl~ Q2' P2' Q3 Queue Ql then contains the series of codes : 20 classified in,increasing order and classification is ended.
In the classification process described hereinbefore, at each iteration a single sequence from storage means Ql is transferred into each of the other storage means. It would also have been possible to distribute all the sequence's contained in storage means Ql into the other storage means in a single operation, in an identical manner to the process described relative to Fig 2b for mechanical sorting systems only having storage means organised in the form of a queue.

In the case of Fig 8 and more generally in the case where the mechanical sorting system has storage means organised in the ~orm of stacks and storage means organised in the form of queues, it is appropriate to take certain precautions during the sequence merging operations. Thus, it is then nec~ssary to ensure that the sequence obtained by merging the sequences at the head of e~ch of the storage means and which is deposited in the storage means organised as queue Ql has a different orientation from the ~inal sequence contained in queue Ql This problem has not occurred in the example described with reference to Fig 8. It is easy to see that this problem occurs when the parity of the number of sequences contained in the storage means Ql before the transfer operations is equal to the parity of the number of storage means involved in the merging operations.
In the example described9 five storage means were used for merging the sequences and the number of sequences contained in queue Ql' prior to transfer, was ~ un;ts and then 4 units. Thus, there was no problem of succession of two sequences with the same orientation in queue Ql~
However, if initially queue Ql only contained 7 sequences, the sequence obtained by merging the sequences at the head of each of the five storage means would have the same orientation as the sequence at the end of the series of sequences contained in Ql One way of obviating this is to transfer one sequence into each of the storage means other than Ql by alternately transferring a sequence into a stack and then into a queue, the first sequence being transferred into a stack, followed by the merging of the sequences at the head of the storage means, other than storage meanS Ql The sequence obtained by merging then has a different orientation from the final sequence of the series of sequences contained in Ql The performance indicator associated with this architecture is equal to logk(m), in which k is the number of storage means and m is the number of sequences which is statistically approximately 2.N/3, in which N is the number of objects to be classified.
The mechanical sorting system shown in Fig 9 has a slightly different architecture from that of Fig 8.
In Fig 9, the number of storage means organised in stack-like~anner is equal to the number of storage means organised in queue-like manner. For example, this number is 3.
The mechanical sorting system thus comprises three queue-type storage means Q19 Q2 and Q3, each providing an introduction element Qi1, Qi2 and Qi3 and an extraction element Qel, Qe2 and Qe3. It also comprises three stack-type storage means Pl, P2 and P3, each provided with an introduction element Pi1, Pi2 and Pi3 and each provided with an extraction element Pe1, Pe2 e 3 ~ 'inally, the mechanical sorting system comprises means for transferring the objects from one storage means to the other and constituted by several branches and branching points.

~ . , s 7907 c-sL

r~ J

The mechanical sorting system of Fig 9 can be deduced from that of Fig 8 by adding a stack-type storage means P3, by eliminating branch 76 in the transfer means and by adding a branch 82 connecting 5witch point B4 to introduction element Pi3 of stack P3, said branch having a switch point B5, a branch 84 connecting switch point B5 to introduction element Qil of queue Ql and a branch 86 connecting extraction element Pe3 to branch 84.
The process for classifying a series of objects by means of the mechanical sorting system of Fig 9 is very similar to that described with reference to Fig 8. As in the case of Fig 8, it mustbe ensured that a merged sequence deposited in queue Ql has a different orientation from the last sequence contained in said queue. This can be controlled in the same way as in Fig 8, e.g. by controlling the respedive parity of the number of sequences contained in queue Ql and the parity of the number of storage means of the mechanical sorting system.
In order to illustrate this, a description will be given of the sorting of the aforementioned series.
The diff~rent steps in the classification process are indicated below. The controls performed are given for each new operation, as well as the successive state of the queues Ql' Q2 and Q3 and the stacks Pl, P2 and P3.
Ql (initial): 576J804/640,300,186/339/199/905/407, 139,94/919/898,419,127.
COntrol: transfer of a sequence from Ql into each of the storage means Q2' P2, Q3 and P3. (If the first ~. I
s 7907 c-sL

~2~' S~

sequence from Ql has been transferred into stack Pl, followed by a sequence into Q2~ P2~ Q3 and P37 the sequence obtained by merging the sequences at the head of each of these storage mean~ would also have an orientation identical to that of the last sequence contained in Ql To obviate this, stack Pl is 7'jumped~
during the sequence transfer operation, which has the effect of changing the orientation of the sequence obtained by merging. This sequence then has a different orientation from that of the last sequence contained in Ql) Ql : 905/407~139,94/919/898,419,127.
Q2 : 576,804.
P2 : 186,3009640.
Q3 : 339.
P3 : 199.
Control: merging the sequences at the head of Ql' Q2 P2, Q3 and P3.
Ql : 407,139,94/919,898,~19,127/186,199,300,339,576, 640,804,905.
Control: transfer of a sequence from Ql into each of the other storage means.
Ql Pl : 94,129,407.
Q2 : 919 P2 : 127,419~898.
Q3 : 186,199,300,339,576,640,804~gO5.

control: merging the sequences at the head of each of the storage means.

.. .

Ql : g4,127,139~186,199,300,339,~07~419,576,640,804, ~98,905,919.
The series of objects is classified.
The classification process described transfers a single sequence from storage means Ql into each of the other storage means prior to each merging operation.
However,the invention is not limited to this sole sequence transfer mode. In particular, a transfer process which brings about the distribution into all the sequence storage means contained in Ql before each merging operation (as clescribed with reference to Fig 2b) is also cvvered by the invention.
The architecture of the mechanical sorting system of Fig 9 is interesting in that it ~ermits, by manipulating certain branching points, to obtain the architectures of preceding drawings. For example, on locking switch point B5 in the position such that branches 82 and 84 are connected, the mechanical sorting system of Fig 9 behaves operationally in the same way as that of Fig 8, stack P3 being placed out of circuit. In the same way, on locking switch points Bl, B3 and B5, in such a way that branches 64 and 68, 70 and 74, 82 ancl 84 are respectively connected, the mechanical sorting system of Fig 9 is operationally identical to the mechanical sorting system not having queue-type storage means shown in Fig 1.
Thus, with a single physical machine, it is possible to perform several functions and consequently use an optimum classification machine for each particular classification problem.

Claims (17)

1. Apparatus for classifying indexed objects, characterized in that it comprises a mechanical sorting system (10) and an electronic control system (20), the sorting system comprising A) a number M, which is positive or optionally zero of object storage means (P1, P2, P3) organised in stack-like manner, i.e. enabling objects to be removed in the reverse order from which they were introduced, each of these means being provided with an element (Pi1, Pi2, Pi3) for introducing objects onto said stack and an element (Pe1, Pe2, Pe3) for extracting the first object from said stack;
B) a number N, which is positive and equal to or greater than M, of object storage means (Q1, Q2, Q3) organised in queue-like manner, i.e. able to remove the objects in the order in which they were introduced, each of these means being provided with an element (Qi1, Qi2, Qi3) for introducing objects into the queue and an element (Qe1, Qe2, Qe3) for extracting the first object from the queue, one of the queue-type storage means constituting a reception means (Q1);
C) a means for transferring or transporting the objects to be classified comprising an introduction branch (30) arranged between an inlet (32) and the reception means introduction element, a branch between the reception means extraction element and the reception means introduction element, said branch being provided with switch points (A, B) for connecting the reception means extraction element (Qe1) to each of the introduction elements (Qi2, Qi3,Pi1 Pi2) of the other storage means and branches for connecting each of the extraction elements (Qe2, Qe3, Pe2, Pe3) of said other storage means to the reception means introduction branch, whilst the electronic control means comprises:
D) a means (50) for reading a numerical code placed on the objects passing along the introduction branch (30);
E) a control computer (60) comprising:
a) a buffer input circuit (62) connected to the reading means (50), b) a memory (64) able to receive the codes from the different objects introduced into the sorting system, said memory having N areas operating in stack-like manner in accordance with the last-in-first-out procedure, N
areas (64Q1, 64Q2,64Q3) operating in queue-like manner according to the first-in-first-out procedure, an area (64I) in which is stored the information indicating for each of the codes of the M+N memory areas whether it is a salient point, a memory area (64T) comprising instructions, the stored codes being classified in the M+N storage areas in the same way as the processed objects are classified in the storage means;
c) a circuit (66) for reading data and instructions stored in the memory;
d) a logic unit (68)for performing instructions and able to:
- decompose the series of codes read by the reading means into monotonic sequences, - store the salient points of the series of read codes, - transfer into each of the storage means other than the reception means, the same number q of sequences of objects from the reception means, - merge by collation the sequences of objects of the same rank of each of the storage means and optionally the reception means, the sequence obtained by merging being stored in the reception means, - iterate the transfer and merging operations while salient points remain in the series of objects from the reception means, the execution of these instructions having the effect of classifying the codes in a given order in a memory area operating in queue-type manner, the logic unit also being able to supply control instructions for displacing the objects corresponding to these codes from one storage means to the other in order to finally obtain the objects classified in the desired order in the reception means, e) a buffer output circuit (69) connected to the logic unit and having outputs connected to the introduction means, to the extraction means and to the switch points.

2. Apparatus according to claim 1, characterized in that, for each iteration, the number q of sequences transferred by the logic unit of the computer from the reception means to the storage means is equal to 1.

3. Apparatus according to claim 1, characterized in that, for each iteration, the number q of sequences transferred by the logic unit of the computer from the reception means into each of the other storage means is equal to the quotient of the division of x+N+M by N+M, in which x is the number of sequences contained in the reception means.

4. Apparatus according to claim 2, characterized in that the number of storage means organised in stack-like manner is zero, so that the series of codes read by the reading means is decomposed by the computer logic unit into monotonic sequences, all the sequences having the same orientation.

5. Apparatus according to claim 4, characterized in that the logic unit is able to merge by collation sequences of the same rank from each of the storage means, other than the reception means and simultaneously to transfer groups of sequences from the reception means into each of the storage means, other than the reception means.

6. Apparatus according to claim 4, characterized in that the reception means of the sequence obtained by collation is, for each iteration, a different storage means.

7. Apparatus according to claim 4, characterized in that the storage means are grouped in stage-like manner, all the stages having a same number of storage means and in that each sequence obtained by collation of sequences at the head of the storage means of one stage is classified in a storage means of another stage, each storage means of said other stage successively receiving a sequence from said stage.

8. Apparatus according to claim 47 characterized in that it also comprises at least one supplementary reading means and a branch for connecting said reading means to at least one introduction element of a storage means of the first stage of the mechanical sorting system.

9. Apparatus according to claim 8, characterized in that it comprises the same number of reading means as there are storage means for each stage, each reading means being connected to the introduction element of a storage means of the first stage of the mechanical sorting system.

10. Apparatus according to claim 2, characterized in that the number M of storage means organised in stack-like manner is not zero, so that the series of codes read by the reading means is decomposed by the computer logic unit into monotonic sequences, two consequently consecutive sequences having different orientations and in that, for each iteration, the logic unit transfers into each of the storage means groups of q sequences of objects, said group being alternately transferred into a queue-type storage means and into a stack-type storage means.

11. Apparatus according to claim 10, characterized in that the mechanical sorting system, comprises M storage means organised in stack-like manner and M+1 storage means organised in queue-like manner, the reception means receiving the list of read codes and in that, for each iteration, the first group of q sequences of objects transferred from the reception means is received in a queue-type storage means.

12. Apparatus according to claim 10, characterized in that the mechanical sorting system comprises M storage means organised in stack-like manner and M storage means organised in queue-like manner, whereof a reception means receives the list of read codes and in that, for each iteration, the first group of q sequences of objects transferred from the reception is received in a storage means organised in stack-like manner.

13. Apparatus for the classification by destination of indexed objects, characterized in that it comprises a mechanical classification system (10) and an electronic control system (20), the classification system comprising:
A) a number N of storage means organised in queue-like manner, i.e. able to remove the objects in the order in which they were introduced, each of these elements being provided for this purpose with an element for introducing the objects into the queue and an element for extracting the first object from the queue, said storage means being arranged in ordered manner, their ranks between 0 and N-1, said storage means optionally being arranged in stage form;
B) a means for transferring the objects to be classified provided with branches and branching points making it possible to connect each extraction element to all the introduction elements, said transfer means also being provided with an introduction branch (30) connected to all the introduction elements and to all the extraction elements;
C) a means for reading a numerical code placed on the objects passing along the introduction branch (30);
D) a control computer (60)comprising:
a) a buffer input circuit (62) connected to the reading means (50), by a memory (64) able to receive the codes of the different objects introduced into the classification system, said memory comprising N areas (64Q1, 64Q2, 64Q3) operating in queue-like manner according to the first-in-first-out procedure, a memory area (64T) comprising instructions, the stored codes being classified in the N memory areas in the same way in which the processed objects are classified in the storage means, c) a circuit (66) for reading data and instructions stored in the memory, d) a logic unit (68) performing the instructions and able to:
- replace the code of each object by a destination code between 1 and d, in which d is the number of possible destinations, - express the new code of each object in a base P, - sort by destination by depositing the objects in the storage means in accordance with a criterion based on the value of the digits of the codes of said objects.

14. Apparatus according to claim 13, characterized in that the storage means are grouped in stage-like manner, the number of stages being equal to the number of digits of the codes of the objects, each stage having P storage means and in that the logic unit (68) performs sorting by destination using the following operations:
- store each object introduced into the classification system in the storage means having as its rank the value of the least significant digit of the code of said object, - iterate for each digit of the code of the objects, in the rising order of the ranks of the digits, the following operation, the successive iterations being performed in consecutive stages and for each storage means, by rising rank of said storage means, the transfer of each object from said storage means into the storage means whose rank is equal to the value of the digit, of standard ranks of the code of said object, - destack the storage means in the order of rising ranks.

15. Apparatus according to claim 13, characterized in that the storage means are grouped in stage-like manner, the number of stages being equal to the number of digits of the codes of the objects, each stage having P-1 storage means and in that the logic unit (68) sorts by destination by using the following operations:
- storing each object introduced into the system, the objects whereof the kth (k + O) starting from the right is equal to i(1 ? i ? P-1) and the k-1 digits from the right are equal to zero being deposited in the queue, in which k indicates the kth stage and i+1 the rank of the storage means in the stage and the objects whereof all the digits are zero being removed from the mechanical sorting system, - taking the objects from stage j and depositing the objects whose kth digit(k>j)starting from the right is equal to i (1 ? i ? P-1) and the k-j digits to the right of the kth digit are equal to zero in the queue Qk,i+1' in which k indicates the kth stage and i+1 the rank of the storage means in the stage and removed from the mechanical sorting system the objects, whereof all the digits of rank equal to or higher than j are zero, said operation being successively performed for each stage j, taken in order and starting from the first stage.

16. Apparatus according to claim 13, characterized in that it comprises several reception means, each of said means being connected to at least one element for extracting the storage means from the final stage of the mechanical classification system.

17. Apparatus according to claim 16, characterized in that it comprises the same number of reception means as there are storage means per stage, each reception means being connected to the elements for extracting a storage means from the final stage of the mechanical classification system.