WO2006094889A1

WO2006094889A1 - Method for processing a linked list of time segments

Info

Publication number: WO2006094889A1
Application number: PCT/EP2006/060043
Authority: WO
Inventors: Geert Machtelinck
Original assignee: Quadrat
Priority date: 2005-03-04
Filing date: 2006-02-17
Publication date: 2006-09-14

Abstract

In an appointment scheduling method an appointment time is determined for a client taking into account the availability of the client, the availability of resources, constraints, and a pre-operative time period and/or a post-operative time period. The pre-operative time period and/or the post-operative time period are adjustable for an individual scheduling operation.

Description

METHOD FOR PROCESSING A LINKED LIST OF TIME SEGMENTS

[DESCRIPTION]

FIELD OF THE INVENTION

The present invention relates to a method of managing occupation of a client (e.g. a patient) in an appointment scheduling system and to a user interface for such an appointment scheduling system. Appointment scheduling systems can be applied in medical institutions, where appointments need to be scheduled for patients, taking into account a multitude of constraints such as the availability of personnel and equipment, and of the patient himself.

BACKGROUND OF THE INVENTION

In appointment scheduling, one part to manage is the resource (such as doctors, examination rooms, examination equipment etc.) occupation, the other part is the client (e.g. patient) occupation. When both come together, it may well be that they do not match in time .

For many examinations and/or procedures, a patient must be present some time before, e.g. to take in a medicine, to undress, to fill in a questionnaire, etc..., without this blocking the occupation of a room or a physician. This time is called pre-operative time (pre- op) . Similarly, a patient must sometimes remain afterwards for similar reasons, again not blocking resources as a room or physician. This time is called post-operative time (post-op) .

This in practice can give way to multiple problems : - Pre and Post-op's may not be communicated to the patient. As a result, the patient arrives just in time. As a consequence the whole schedule of all concerned resources is shifted by a number of minutes

Pre and Post-op times are no fixed times : they differ by procedure and by patient. Additionally, they are hard to put in rules, because so many factors may play a role to determine them. So in case fixed times were used and taken into account in planning, the risk of ineffective resource management remains .

Existing appointment scheduling systems such as the system marketed by Agfa-Gevaert N.V. and denoted by the trade name Qplanner, take into account pre-op and post-op times. However, these times are pre-defined and fixed.

Additionally, during the scheduling process of determining an appointment date with the patient, the appointment start time does not include the pre-op time. As such, a wrong appointment time can be communicated.

It is an aspect of the present invention to provide a method and a user interface that overcome the disadvantages of the prior art.

SUMMARY OF THE INVENTION

The above-mentioned aspects are realized by a method of managing client occupation in an appointment scheduling system as set out in claim 1.

Specific features for preferred embodiments of the invention are set out in the dependent claims .

An appointment time for a client is determined taking into account the availability of the client, the availability of at least one resource and at least one of a pre-operative time period and a postoperative time period. According to the present invention at least one of the pre-operative time period and said post-operative time period is adjustable for an individual scheduling operation.

In the context of this invention a pre-operative time period is a time period preceding the actual examination wherein the client

(patient in a medical appointment scheduling system) must be present but during which the resources do not need to be reserved for this appointment .

Like-wise a post-operative time period is a time period after the actual examination wherein the client (patient in a medical appointment scheduling system) must be present but during which the resources do not need to be reserved for this appointment. Examples are given in the introductory part of the specification.

In the context of a medical appointment scheduling system the term 'resource' refers to all kinds of resources such as examination rooms, examination equipment etc. as well as to human resources such as doctors, operators etc.

In a specific embodiment pre-operative and/or post-operative time period are variable time periods, the actual values of which are input into the system for each individual scheduling operation by the person in charge of scheduling.

Constraints on specific pre- and post-operative time periods can be set, these constraints can be set in advance or can be set by the person in charge of scheduling.

It is also possible to adjust these pre-operative and/or post- operative periods for consecutive procedures.

In a specific embodiment a constraint regarding pre-operative and/or post operative periods may be set for a certain procedure or set of consecutive procedures.

An example is overlap between the post-operative time period of one procedure and the pre-operative time period of a consecutive procedure . Another aspect of the present invention relates to a user interface for an appointment scheduling system.

The user interface has input means for data on at least one of pre- operative and post-operative time periods. These input means are arranged to communicate the data to a scheduling engine in which the data are taken into account when determining an appointment .

In one embodiment the user interface additionally has means for inputting data on a constraint concerning pre-operative and postoperative time periods of consecutive procedures in a scheduling operation, such as overlap between post-and pre-operative time periods of consecutive procedures, and for communicating these data to a scheduling engine in which the data are taken into account when determining an appointment .

An example of a scheduling engine for an appointment scheduling system is described extensively in an application entitled 'Method for processing linked lists of time segments' , filed by the same applicant on the day of filing of the present application.

In this application is described how a collection of possible solutions for scheduling an appointment for a client (e.g. a patient in a hospital) is determined taking into account pre-op and post-op times set by the scheduler. The described method is an embodiment illustrating a possible implementation of the method of the present invention.

The embodiments of the methods of the present invention are generally implemented in the form of a computer program product adapted to carry out the method steps of the present invention when run on a computer .

The computer program product is commonly stored in a computer readable carrier medium such as a CD-ROM. Alternatively the computer program product takes the form of an electric signal and can be communicated to a user through electronic communication. Further advantages and embodiments of the present invention will become apparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1 - 3 are screen shots illustrating embodiments of a user interface according to the present invention.

Figure 4 describes a set of actions related to resources and connected by comprising, relational and sequential links;

Figure 5 describes a reduced set of actions that is left after working out the relational links according to a preferred embodiment ;

Figure 6 describes a reduced set of actions that is left after working out the relational and comprising links according to a preferred embodiment;

Figure 7 describes a reduced set of actions that is left over after working out the relational, comprising and sequential links according to a preferred embodiment; Figure 8 describes a set of time windows associated with actions;

Figure 9 demonstrates the processing of a relational link according to a preferred embodiment;

Figure 10 demonstrates the processing of a comprising link according to a preferred embodiment; Figure 11 demonstrates the processing of a sequential link with a preceding action according to a preferred embodiment;

Figure 12 demonstrates the processing of a sequential link with a following action according to a preferred embodiment;

Figure 13 demonstrates the processing of a sequential link with a following action, taking into account slack time according to a preferred embodiment;

Figure 14 shows an example of processing a relational link according to a preferred embodiment;

Figure 15 shows another example of processing a relational link according to a preferred embodiment; Figure 16 shows three examples of processing a comprising link according to a preferred embodiment;

Figure 17 shows an example of the processing of time windows according to a preferred embodiment; Figure 18 shows an example of using deductive logic; Figure 19 shows an example of using inductive logic- Figure 20 shows a data processing system according to a preferred embodiment of the current invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention provides the possibility to adapt the pre and post-op times during the creation of an appointment.

The person who is in charge of scheduling an appointment with an appointment scheduling system bases the data that are inputted in the system on the information received by the patient and on his knowledge of the procedure at hand. Typical information can be patient's age, patient's weight, patient's mobility, patient allergies, etc. and this in relation to the procedure pre or post-op requirements such as the intake of a medicine (large influence of allergies or other specific clinical conditions) , undressing (large influence of age) , needed to lie on a table or not (large influence of mobility) .

Figure 1 shows a screen shot of a user interface for an appointment scheduling system. The user interface has a field in which the person in charge of scheduling can fill in the duration of pre-op and post-op times. These data are input in the underlying scheduling engine and taken into account when calculating the data on the appointment .

Similarly, when scheduling consecutive procedures, one can indicate this for each of the procedures. It may well be that because the procedures are now consecutive (and not stand-alone) the influence on the pre- and post-operative times is different. In a specific embodiment of the present invention it is possible to define that the post-op time of one examination and the pre-op time of the following examination must overlap, s is illustrated in figure 2.

Because of these possibilities, the patient's occupation is managed correctly and as a consequence, the resources' occupations are not disturbed. Data on the patient's occupation and on the occupation of the resources can be displayed (see figure 3) .

Additionally, during the search and determination of a possible appointment in consultation with the patient, the possible start times and end times which are communicated include the pre-op (and post-op) time. Consequentially the patient is well aware of this. At the moment the start time and end time are confirmed, the person who is in charge of scheduling the appointment can then run through the details and inform the patient e.g. that the first 10 minutes of the appointment consist of an intake of a medicine, followed by the actual procedure .

Below aspects of the underlying scheduling method, more specifically of the method of generating a solution space, are described extensively.

Before explaining the general principles of the scheduling method, the method is first explained by working out a specific example, which is also one specific embodiment of the current invention.

According to the example, an appointment needs to be scheduled to examine a patient by means of a scanner. The patient needs to undress before and to dress again after the scan.

The exam itself takes 2 hours. Both for undressing and dressing one hour is provided. After the patient has undressed, he does not want to wait for the exam. When the exam is finished, he accepts that he may have to wait up to one hour before he can dress again.

Figure 4 describes the actions that are part of the appointment and the relations between them. The appointment (100) action comprises three other actions: the undressing (110) action (also called preoperative action), the actual exam (120) action and the dressing (130) action (also called post-operative action) . This comprising relationship is represented by three comprising links (190, 191, 192) between the individual actions (110, 120, 130) and the appointment (100) action. The appointment (100) action is called a parent relative to the undressing (110), the actual exam (120) and dressing (130) actions which are called children. Because of the parent-child relationship of a comprising link (190, 191, 192), it is not symmetrical.

An action is defined as being "atomic" when it does not comprise other actions. For example, the undress (110) action is atomic, but the appointment (100) action is not.

The undressing (110) , the actual exam (120) and dressing (130) actions follow sequentially and this relationship is represented by the sequential links (193, 194). The sequential nature implies that such a link is not symmetrical, as the arrows in Figure 4 also indicate.

The exam (120) can only be carried out when the scanner (140) is available. This kind of relationship is represented by a relational link (183) . In addition does carrying out the exam require the availability of an operator, so a relational link (184) also exists between the exam and the operator (150) . A relational link between two actions indicates that both actions can only be carried out at the same time. From this follows that such a link is by nature symmetrical and transitive. The transitivity is expressed in Fig. 1 by the dotted line (185) between the scanner and operator action. In a more general case, a procedure or exam is preceded by a pre-op action and followed by a post-op action. In a more general case an action refers to an activity related to a resource. Such a resource can be a patient, a physician, a nurse, an operator a diagnostic or treatment apparatus, a examination or treatment room, or any other kind of resource with which an activity can be associated. The resource can or can not be related to the domain of healthcare. The activity can be the use of equipment, the presence of a person, the occupation of a facility or any other activity that refers to the use or availability of any resource. In a more general case any topology of any number of actions related by comprising, relational or sequential links is possible.

Figure 8 shows how with each action (100, 110, 120, 130, 140, 150, 160, 170) in Figure 4 a corresponding time window (501-507) is associated. A time window consists of a linked list of non contiguous time segments, each segment having a beginning and an ending time. For example, for the patient (160) action, the linked list consists of the time segments (510, 511, 512) .

A time window can represent the range of time when an action can potentially occur. However, a time window can also represent a range of time when the action can start or when it can end.

In the example in Figure 8, the time windows (500-503) of the patient (150), the dressing room (170), the scanner (140) and the operator (150) are part of the problem definition data. These time windows represent constraints imposed by the corresponding resources. The time windows (504-507) of the undressing (110), exam (120) and dressing (130) actions and of the appointment (100) as a whole, however, are initially undetermined, as they are the subject of the solution that has to be calculated for the scheduling problem. An undetermined time window is represented as one contiguous time segment with the length of the time window. For example, 508 is the initial time window associated with the exam action (120) . As a solution for the time scheduling problem is being processed according to the current invention, the number of segments of an undetermined time window may change and the beginning and end times of the remaining time segments may become increasingly more focused, until they represent a situation that is consistent with all the constraints imposed by the resources.

Since the constraints imposed by the resources are represented by relational (180-185), comprising (190-192) and sequential (193, 194) links, processing the solution essentially comes down to working out these links.

When working out the links, a number of different cases are to be distinguished that correspond with the different nature of the links (relational, comprising or sequential), the interpretation of the time window of the action (start times, end times or action times), and the relative location of the time segments (the way that the time segments in the time windows of the linked actions overlap) . The result of processing a link involves adjusting the time segments in the time windows corresponding to the linked actions in a way that they become consistent with the constraints imposed by the corresponding resources .

In the following paragraphs the processing of the different links is discussed.

First case: time window processing for actions connected through relational links

Figure 9 illustrates a number of situations for actions connected through relational links, of which the time segments occur in different relative positions (overlapping and non-overlapping) . The interpretation of the time windows (620-623) is that the represent the time during which the action (600-603) can take place. Since the meaning of a relational link is that the two actions (600,601) can only take place simultaneously, the effect of working out the link is that each time window (620,621) should be replaced by a time window (622,623) that consists of time segments (612,613) that are the cross sections of the time segments (610,611) in the original time windows.

Because of the transitive nature of a relational link, if an action has more than one relational link - directly or indirectly - to another action, the time windows of all the actions are to be replaced by a time window of which the time segments are the cross sections of all the time segments of the time windows of all the related actions.

Second case: Time window processing for actions connected through comprising links

Figure 10 illustrates a number of situations for actions connected through comprising links, of which the time segments occur in different relative positions (overlapping and non-overlapping) . The interpretation of the time windows (700-702) is that the represent the time during which the action can take place. The meaning of a comprising link is that the time segments (711) of a child action (701) have to occur within the time segments (710) of the time window (720) of the parent action (700) . This is achieved by replacing the time segments (711) of the time window (721) of the child action (701) by the cross section (712) of themselves (711) with the time segments (710) of the time window (720) of the parent action (700) .

Third case: Time window processing for actions connected through sequential links

The following terms are introduced or clarified:

- time window of an action: linked list of time segments describing when an action can take place.

- time window of start times of an action: linked list of time segments describing when said action can start; - time window of end times of an action: linked list of time segments describing when said action can end;

The time window of an action, the time window of start times of the same action and the time window of end times of that same action are interrelated.

Referring to Figure 12 and according to an embodiment of the current invention, a time window (921) representing start times (911) of an action is calculated from a corresponding time window (920) representing said action, by subtracting from the end times of the time segments (910) in the latter time window (920) the duration (930) of said action.

Referring to Figure 11 and according to an embodiment of the current invention, a time window (821) representing end times is of an action is calculated from a corresponding time window (820) representing said action, by adding to the start times of the time segments (810) in the latter time window (820) the duration (830) of the action.

According to an embodiment of the current invention time windows representing start times and end times of an action are also interrelated by shifting the start and end times in the time segments by the duration of the action.

According to one embodiment of the current invention, when a first preceding action (800, 902) is followed by a second following action (802, 900), certain restrictions are applied on both the start and end times of both actions.

A first restriction involves the start times of a following action in order to achieve that that the start times of a following action can never be earlier than the earliest end time of any of the preceding actions. According to one aspect of the current invention, this effect is achieved by replacing the time segments (813) of the start times (823) of the following action (802) by the cross section (814) between themselves (813) and the time segments (811) of the end times (821) of the preceding action (800) .

A second restriction involves the end times of the preceding action in order to achieve that the end times of a preceding action can never be later than the latest start times of any of the following actions. According to one aspect of the current invention, this effect is achieved by replacing the time segments (913) of the end times (923) of the preceding action (902) by a cross section (914) between themselves (913) and the time segments (911) of the start times (921) of the following action (900) .

In the case that slack time is allowed between two actions, the end times of the time segments of the preceding action are preferably extended by the maximum allowed slack time, prior to applying said first restriction. Referring to Figure 13, the time window (1020) of the preceding action (1000) is used to calculate the time window (1021) of the end times (1001) of the preceding action (1000) by shifting the start times of the time segments (1010) forward by the duration (1030) of the preceding action (1000). Following that, the segments (1011) of the time window (1021) of the end times (1001) of the preceding action are extended by the maximum slack time (1040) to yield the time segments (1012) of the time window (1022) of the end times (1002) of the preceding action plus the slack time. To obtain the time window (1024) of the start times of the following action (1004) , the end times of the segments (1013) of the time window (1023) of the following action (1003) are shifted backwards by the duration (1050) of the following action (1003) . The segments (1015) of the time window (1025) of the start times of the following action (1005) are obtained by making the cross section between the time segments (1012) and the time segments (1014) .

Working out a sequential link between two actions involves applying the two above restrictions. Having described how according to the current invention:

- relational links are processed (1) ;

- composite links are processed (2);

- the relation between time windows representing actions, start times and end times (3) is processed;

- sequential links are processed (4) ;

- slack time is processed in sequential links (5) .

we proceed next by working out the example that was earlier introduced according to the principles of the current invention.

The problem that has to be resolved is finding the time window representing the start time(s) for the exam.

A first step consists of working out the relational links in Figure 4.

Referring to Figure 14, this is done by using the general principles according to the current invention that were earlier explained by means of Figure 9.

Similarly, referring to Figure 15, the relational links can be worked out between the exam, the operator and the scanner.

After this operation, the graph in Figure 4 can be reduced to the one in Figure 5, with the notion that he time windows associated with the appointment and the exam actions are not the original ones, but the ones that were obtained from the previous step.

A second step consists of working out the comprising links in the graph in Figure 5. According to the current invention, this is achieved by processing the time segments in the time windows of the undress, exam and dress actions so that they fall within the time segments of the time window of the appointment action. This is demonstrated in Figure 16A, 16B and 16C using the general principles of the current invention that were earlier explained by means of Figure 10.

After this operation, the graph in Figure 4 or Figure 5 can be reduced to the one in Figure 6, with the notion that he time windows associated with the undress, exam and dress actions are not the original ones, but the ones that were obtained from the previous step.

The third step consists of working out the constraints imposed by the sequential links.

The exam action is preceded and followed by another action. According to one aspect of the current invention, this has implications on start and end times of the time segments of the corresponding time windows.

Referring to Figure 17, the start times (1310) of the exam should never be earlier than the earliest end times (1307) of the undress action, and the end times (1303) of the exam including slack time should never be later than the latest start times (1301) of the dressing action, according to the general principles that were earlier explained by means of Figure 11, 12 and 13.

After this operation, the graph in Figure 4, 5 and 6 can be reduced to the one in Figure 7, with the notion that he time window associated with the exam actions are the ones that were obtained from the previous step.

Introducing deductive and inductive logic

According to a preferred embodiment of the current invention, an inductive logic method is used to control the processing of the time windows as opposed to deductive logic. These terms are explained in more detail . Generally speaking, deductive logic starts with variables of which the values are known (called "the hypotheses") and deduces step by step according to a predefined flow the value of the variable for which a solution is sought (called the "final conclusion"). This processing occurs through the calculation of the value of intermediate values (called "intermediate conclusions").

In deductive logic, the information processing flow itself is the subject of the programming and as a result, once it has been programmed, it is fixed. Therefore, deductive logic programming is efficient for those problems of which the taxonomy of relations between variables is fixed, and only the values of the hypotheses are subject to change.

An example of a deductive logic method is shown in Figure 18. Hl₇ H2 and H3 are the basic hypotheses. Processing (151) the hypothesis H2 results in the intermediate conclusion Cl. Processing (152) the conclusion Cl and the hypothesis Hl results in the intermediate conclusion C2. Processing (153) the conclusion C2 and the hypothesis H3 then leads to the final conclusion C3.

In contrary, the entry point for an inductive logic method according to the current invention is the final conclusion itself of which the value is initially unknown. By means of a set of inductive steps that take the form of an exploration process, the data of the hypotheses is first gathered and then systematically processed to calculate the final conclusion.

An inductive step to calculate an (intermediate) conclusion comprises determining what other variables are needed to calculate said (intermediate) conclusion. There are two possibilities:

1) Either the values of the variables that are needed are known because they are either hypotheses or intermediate conclusions of which the value has been earlier determined; in that case the variables can be processed to obtain the (intermediate) conclusion. 2) Or at least one of the variables that are needed is an intermediate conclusion of which the value has not been determined yet; in that case this (intermediate) conclusion initiates a new inductive step.

The subject of the programming in an inductive logic method is not a deductive information processing flow, but a rule set that manages the inductive steps.

Developing a rule set for an inductive method involves determining:

1) the nature (classes) of the variables (intermediate conclusions) that are needed to calculate a conclusion;

2) for each nature (class) of a variable (intermediate conclusion) determining what kind of processing on what other variables (other intermediate conclusions or hypotheses) is needed to calculate the result of said (intermediate) conclusion.

Unlike in a deductive logic method, the problem definition now not only states the values of the hypothesis, but also the taxonomy of the relations between the variables. This allows for far greater flexibility when solving problems that have different taxonomies of relations between variables. Once the rule set has been programmed, problems with a wide variety of taxonomies of relations between the above variables can be solved using the same program.

An example of using an inductive logic method is presented in Figure 19. The entry point is a call to calculate the value of the variable C3. The rule set dictates that the variable C3 requires the processing of two other variables being H3 , of which the value is known since it is a hypothesis, and the intermediate conclusion C2, of which the value at this point is unknown. The latter causes a new inductive step to calculate the unknown variable C2. The rule set dictates that the variable C2 requires the processing of two other variables Hl, of which the value is known since it is a hypothesis, and of the intermediate conclusion Cl, of which the value at this point is unknown. The latter causes a new inductive step to calculate Cl. The rule set dictates that the variable Cl requires the processing of the variable H2 , of which the value is known. This results in the processing of H2 to obtain Cl. Now that Cl is known, this results in the processing of Cl and Hl to calculate C2. Now that C2 is known, this results in the processing of C2 and H3 to calculate the final conclusion C3.

Preferred embodiment based on inductive logic

According to the current invention, the solution of the scheduling problem stated in the above example is preferably carried out by using an inductive logic method.

According to one embodiment, the following classes or variables are used for managing resources : time window related to an action time window related to the start times of an action time window related to the end times of an action

According to the same embodiment the inductive logic is managed by a set of three rules : a first rule dictates that obtaining the value of a variable of the type "start times of an action" requires the processing of the value of the "end times of that action" and the value of "the previous action" . a second rule dictates that obtaining the value of a variable of the type "action" requires the processing of the values of the "parent actions" and the "related actions" . a third rule dictates that obtaining the value of a variable of the type "end times of an action" requires the processing of that same "action" , the "slack time" and "the following action" . In a more general case other sets of rules can be selected that however yield equivalent results and also fall within the scope of the current invention. This follows from the fact that the classes of variables in the above rule set are related to each other by simple relationships.

We have found that the above set of three classes of variables in combination with the above three rules provides a self contained method than enables resource scheduling and management of a wide variety of situations.

The method according to the current invention processes time windows and results in a time window that generally comprises a plurality of time segments, each one indicating a single solution of when the corresponding action can take place (or start) . The method hence produces not just one solution for the scheduling problem, as in the prior art, but a complete set of solutions also called a solution space .

The method according to the current invention can be used for any resource scheduling and management problem that can be modelled as a set of actions corresponding to resources that are related by a combination of comprising, relating and sequential links and slack time .

Having described the general principles of the current invention we proceed by working out the example that was earlier introduced.

Referring to Figure 17, the method starts by instantiating a variable start times exam, which is the final conclusion of the scheduling problem.

The symbols in the circles on one of the figures 14 to 17 indicate references to the same symbols in circles in one of the other figures . Since the value of the variable start times exam at this point is unknown, this induces an inductive step (ISl) . The first rule according to the current invention dictates that in order to calculate the value (1410) of the start times of the exam, the values (1408=1405) of the end time of the exam action and

(1406=1302) of the undress action are needed. Since none of these values are known at this time, this causes two new inductive steps: a first one (IS2) to enable the calculation of the value (1406=1302) of the undress action and a second one (IS3) for the calculation of the value (1408=1405) of the end times of the exam.

We proceed by first explaining the inductive step (IS2) . Referring to Figure 14 to 17, the second rule dictates that in order to calculate the value (1406=1302) of the undress action requires the processing of the value (1300=1103) of the appointment action which is the parent action. Since the value (1300=1103) of the appointment action is not known at this time, this induces again an inductive step (IS4) for the calculation of that variable. Since this variable (1300=1103) appointment is of the type "action", the same (second) rule applies, requiring the processing of the values of related dressing room (1101) and patient (1100) actions. The values of these actions are known since they are hypotheses, so this enables to calculate the value of the appointment (1300=1103) action and subsequently of the undress (1406=1302) action.

We next proceed by describing the inductive step (IS3) . Referring to Figure 14 to 17, the third rule dictates that the calculation of the value (1408=1405) of the end times of the exam requires the processing of the value (1402=1308) of the exam action and of the value (1400=1305) of the dress action. Since the variable

(1402=1308) of the exam action is of the type "action", the second rule applies, and this requires the processing of the values of the parent appointment (1306=1103) action, and of the related scanner (1200) and operator (1201) actions. The value (1306=1103) of the parent appointment action is calculated the same way as in the inductive step (IS2). The values (1200, 1201) of the relating actions are known, since they are hypotheses, so this enables to calculate the value of the exam (1402=1308) action. Since the variable (1400=1305) is also of the type action, the second rule is applied once more, leading to the processing of the values of the variables (1303=1103) and (1304=1101) . At this point the calculation of the value (1408=1405) of the end times of the exam can be completed and subsequently the calculation of the value (1410) of the start times of the exam.

The above mentioned invention is preferably implemented using a data processing system such as a computer. An embodiment of such a system (1700) is shown in Figure 20. A computer comprises a network connection means (1750, a central processing unit (1760) and memory means (1770) which are all connected through a computer bus (1790) . The computer typically also has a computer human interface for inputting data (1710, 1720) and a computer human interface for outputting data (1730) . According to one embodiment, the computer program code is stored on a computer readable medium such as a mass storage device (1740) or a portable data carrier (1790) which is read by means of a portable data carrier reading means (1780) .

Having described in detail preferred embodiments of the current invention, it will now be apparent to those skilled in the art that numerous modifications can be made therein without departing from the scope of the invention as defined in the appending claims.

Claims

[CLAIMS]

1. Method of managing client occupation in an appointment scheduling system wherein a scheduling operation comprises determining an appointment time for a client taking into account availability of the client, availability of at least one resource and at least one of a pre-operative time period and a post-operative time period characterized in that at least one of said pre-operative time period and said post-operative time period is adjustable for an individual scheduling operation.

2. A method according to claim 1 wherein a scheduling operation comprises scheduling consecutive procedures and wherein a constraint is imposed that the post-operative time period of one procedure must overlap with the pre-operative time period of a consecutive procedure .

3. A method according to claim 1 wherein an appointment time for a client is determined by computing a solution space by the steps of - defining relationships between actions of available resources having associated action constraints, said actions being described by means of time windows comprising linked lists of time segments describing ranges of start times or end times or duration times, and said relationships belonging to the set comprising relational, comprising or sequential relationships;

- identifying a set of resources of a certain kind,

- processing said time windows to determine possible solutions for the actions of the identified resources;

- selecting an appointment time for said client from said possible solutions, wherein said processing comprises an inductive logic step.

4. A method according to claim 3 wherein one of said actions is a pre-operative action with which said pre-operative time period is associated and/or one of said actions is a post-operative action with which said post-operative time period is associated.

5. The method according to claim 3, wherein the inductive logic step comprises one of the following: - obtaining a time window of start times of an action by processing a time window of end times of said action and a time window of a previous action,

- obtaining a time window of end times of an action by processing a time window of said action, a time window of a following action and a slack time,

- obtaining a time window of an action by processing the time windows of actions that are either a parent action or related actions .

6. The method according to claim 3, wherein the inductive step of obtaining a time window (1430) of start times (1410) of an action by processing a time window (1428) of end times (1408) of said action and a time window (1426) of a previous action (1406) comprises the following steps:

- adding the duration (1463) of said previous action (1406) to the start times of the time segments (1446) of the time window (1426) of said previous (1406) action to obtain a time window (1427) of the end times (1407) of said previous action;

- shifting the time segments (1448) of the time window (1428) of the end times (1408) of said action backward by the duration (1464) of said action to obtain a time window (1429) of the start times (1409) of said action;

- obtaining a time window (1430) of the start times (1410) of said action of which the segments (1450) are the cross section of the segments (1447) of the time window (1427) of the end times (1407) of the previous action and the segments (1449) of the time window (1429) of the start times (1409) of said action.

7. The method according to claim 3, wherein the inductive step of obtaining a time window (1425) of end times (1405) of an action by processing a time window (1422) of said action (1402), a time window (1420) of a following (1400) action and at least one of a preoperative time period or a post-operative time period (1461) comprises the following steps:

- subtracting the duration (1460) from the end times of the time segments (1440) of the time window (1420) of said following action (1400) to obtain a time window (1421) of start times (1401) of said following action;

- adding the slack time (1461) to the end times of the time segments

(1442) of the time window (1422) of said action (1402) to obtain a time window (1423) of said action plus slack (1403);

- adding the duration (1462) to the start times of the time segments

(1443) of the time window (1423) of said action plus slack (1403) to obtain a time window (1424) of end times (1404) of said action;

- obtaining a time window (1425) of end times (1405) of said action of which the time segments (1445) are the cross section of the time segments (1441) of a time window (1421) of start times (1401) of said following action and the time segments (1444) of a time window (1424) of end times (1404) of said action.

8. The method of claim 3, wherein the inductive step of obtaining a time window of an action by processing the time windows of actions that are either a parent action or related actions comprises the following steps:

- replacing the time segments of time windows of related actions by- time segments that are the cross sections of the original time segments of said time windows of said related actions;

- adjusting the begin and end times of time segments of children actions so that are comprised in the time segments of the time window of the parent action.

9. A method according to claim 1, wherein at least one of said resources is a patient, a physician, a nurse, a medical diagnostic apparatus, a medical treatment apparatus, an examination room or a treatment room.

10. A user interface for an appointment scheduling system comprising s input means for data on at least one of pre-operative and postoperative time periods, said means being arranged to communicate said data to a scheduling engine in which said data are taken into account when determining an appointment .

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11. A user interface according to claim 10 comprises means for inputting data on a constraint concerning pre-operative and postoperative time periods of consecutive procedures in a scheduling operation, said means being arranged to communicate said data to a scheduling engine in which said data are taken into account when s determining an appointment .

12. A user interface according to claim 11 wherein said constraint is the requirement of overlap between post-and pre-operative time periods of said consecutive procedures. 0

13. A computer program product adapted to carry out the method of any of claims 1 to 9 when run on a computer.

14. A computer readable medium comprising computer executable 5 program code adapted to carry out the steps of any of claims 1 to 9.B

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