JP2005346486A - Document retrieval device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a document retrieval device capable of supporting selection of classification codes being a search key and easily retrieving documents. <P>SOLUTION: The document retrieval device comprises steps of: receiving an input of a text which is a search condition; extracting at least one string of characters being a first search key as a keyword from the text; extracting the first group of documents related to respective extracted keywords from database; referring to the first group of documents extracted for respective keywords; obtaining a list of classification codes for respective keywords which are produced by using at least a part of the classification codes correlated to the first group of documents; retrieving a second group of documents regarding a key classification code from the database for obtaining by using the list of classification codes for respective keywords and by determining the key classification code being the second retrieval key, and presenting the second group of documents as retrieved results. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a document retrieval apparatus that retrieves documents such as patent documents and scientific and technical documents from a database.

The accumulated amount of literature materials such as scientific and technical literatures and patent literatures is increasing year by year, and there is a need for a technique for finding target literature materials from a huge amount of literature materials. For example, if it is a patent document, it is devised to make it easy to find a target document material by performing a search by limiting the technical field according to the International Patent Classification (IPC). An apparatus that searches English documents and Japanese documents simultaneously is disclosed in Patent Document 1.
JP 2001-337981 A

  However, in the above conventional search technology or the like, a keyword search is performed for all documents stored in the document database. For example, a keyword such as “vibration” is likely to be included in a wide range of documents. It becomes difficult to narrow down only.

  On the other hand, it is empirically known that the search accuracy can be improved by narrowing down by classification code (for example, international patent classification), but selection of a classification code as a search key is not easy.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a document search apparatus that supports selection of a classification code as a search key and can easily search for a document.

  The present invention for solving the problems of the above-described conventional example is a document that is connected so as to be accessible to a document database holding a plurality of documents associated with a classification code, and satisfies a given search condition from the document database. A document search device for searching for text, a means for accepting input of text as a search condition, a keyword extraction means for extracting at least one character string as a first search key from the text as a keyword, and the document database The first document group related to each of the extracted keywords is extracted, the first document group extracted for each keyword is referenced, and at least a part of the classification code associated with the first document group is used. Generated for each keyword A list acquisition unit that acquires a list of class codes, a determination unit that determines a key classification code as a second search key using the list of classification codes for each keyword, and a key classification determined by the determination unit Search means for obtaining a second document group related to the key classification code from the document database using a code, wherein the second document group is presented as a search result.

  In addition, the present invention for solving the problems of the conventional example can access a first document database that holds a plurality of documents associated with a classification code and a second document database that has a search index for the classification code. Connected to the first or second document database for searching for a document satisfying a given search condition, the document search device accepting input of text as a search condition, A keyword extracting means for extracting at least one character string as a search key as a keyword; and a first document group related to each of the extracted keywords is extracted from the first document database; Refer to the extracted first document group. A list acquisition means for acquiring a list of classification codes for each keyword, generated using at least a part of the classification codes associated with the first document group, and a list of classification codes for each keyword, And determining the key classification code to be a search key of 2 and using the key classification code determined by the determination means, the key classification code is determined from the first or second document database. Search means for acquiring a second document group, wherein the second document group is presented as a search result.

  Here, the classification code and the character string related to the key classification code determined by the determining means are connected to the classification code database that holds the classification code and the character string related to the classification code in association with each other. It is good also as including the presentation means which acquires from and presents the said acquired character string.

  Further, based on a keyword extracted from the text, a central concept word related to the content of the input text is acquired, and at least a part of a classification code related to the central concept word is acquired to classify each keyword. A second list generating means for generating a second list of codes, wherein the determining means uses the list of classification codes for each keyword and the second list as a second search key; The classification code may be determined. At this time, at least a part of the extracted keywords may be selected according to a predetermined rule, and the selected keywords may be acquired as central concept words related to the contents of the input text.

  Further, the present invention for solving the problems of the conventional example is given from a document database using a computer connected to a document database holding a plurality of documents associated with the classification code. A document search method for searching for a document satisfying a search condition, accepting input of text as a search condition, extracting at least one character string as a first search key from the text as a keyword, and the document database The first document group related to each of the extracted keywords is extracted, the first document group extracted for each keyword is referenced, and at least a part of the classification code associated with the first document group is used. Generated for each keyword A list of issue numbers, using the list of classification codes for each keyword, determining a key classification code as a second search key, and using the determined key classification code, from the document database, A second document group related to the key classification code is acquired, and the second document group is presented as a search result.

  In addition, the present invention for solving the problems of the conventional example accesses a first document database that holds a plurality of documents associated with a classification code and a second document database that has a search index for the classification code. A document search method for searching a document satisfying a given search condition from the first or second document database using a computer that is connected to the computer, accepting input of text as a search condition, Extract at least one character string as a first search key from the text as a keyword, extract a first document group related to each of the extracted keywords from the first document database, and extract for each keyword The first document group A key that is generated using at least a part of the classification codes associated with the document group, obtains a list of classification codes for each keyword, and serves as a second search key using the classification code list for each keyword Determining a classification code, using the key classification code determined by the determination means, obtaining a second document group related to the key classification code from the first or second document database, and The second document group is presented as a search result.

  Furthermore, the present invention for solving the problems of the conventional example described above provides a computer connected to a document database that holds a plurality of documents associated with a classification code, and a search condition provided from the document database. A document search program for searching for a document that satisfies the following conditions: a procedure for accepting input of text serving as a search condition; a procedure for extracting at least one character string serving as a first search key from the text as a keyword; A first document group related to each of the extracted keywords is extracted from the document database, the first document group extracted for each keyword is referred to, and at least a part of the classification code associated with the first document group Generated using A procedure for obtaining a list of classification codes for each word, a procedure for determining a key classification code as a second search key using the list of classification codes for each keyword, and the determined key classification code And obtaining a second document group related to the key classification code from the document database, and causing the computer to execute the second document group as a search result.

  Furthermore, the present invention for solving the problems of the conventional example accesses a first document database holding a plurality of documents associated with a classification code and a second document database having a search index for the classification code. A program for allowing a computer connected to search a document satisfying a given search condition from the first or second document database, and receiving the input of text as a search condition, and the text And extracting at least one character string as a first search key as a keyword from the first document database and extracting a first document group related to each of the extracted keywords from the first document database. Refer to the extracted first document group, A procedure for obtaining a list of classification codes for each keyword, generated using at least a part of the classification codes associated with the first document group, and a list of classification codes for each keyword, Using a procedure for determining a key classification code to be a search key and the key classification code determined by the determination means, the second document related to the key classification code from the first or second document database. And a procedure for acquiring a group is executed by a computer, and the second document group is presented as a search result.

  Embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the document search device according to the embodiment of the present invention includes a control unit 11, a storage unit 12, a storage unit 13, an operation unit 14, and a display unit 15. Yes.

  The control unit 11 is realized by a CPU (Central Processing Unit) or the like, and operates according to a program stored in the storage unit 12. In the present embodiment, the control unit 11 performs processing for extracting a keyword from a search condition, processing for determining a classification code (key classification code) serving as a search key using the extracted keyword, and the key classification code. And a process for searching for a document using. Details of these specific processes will be described in detail later.

  The storage unit 12 includes a memory element such as a RAM (Random Access Memory), and stores a program executed by the control unit 11. The storage unit 12 also operates as a work memory that holds various data used in the process of the control unit 11.

  The storage unit 13 includes a computer-readable recording medium such as a hard disk device, and stores a program executed by the control unit 11. When processing is performed by the control unit 11, the program is read from the storage unit 13, stored in the storage unit 12, and used for processing. The storage unit 13 stores a document database that holds a plurality of documents to which classification codes are assigned in advance. Furthermore, the storage unit 13 holds a dictionary database that stores a keyword and a classification code to be assigned to a document related to the keyword in association with each other.

  Specifically, the document database held by the storage unit 13 holds a plurality of documents and a classification code associated with each document (FIG. 2). In the description of the present embodiment, as a specific example, a case where this document is a patent document and a scientific and technical document will be described as an example.

  In addition, each document has a type of a predetermined edition (for example, the seventh edition if it is later than January 2000) in the international patent classification if it is a patent document, for example, depending on the issue date, issuing organization, etc. Usually, a classification code is assigned, but in this embodiment, the classification codes assigned to the documents stored in the document database are unified into one kind of classification code (unified code) in advance. Has been.

  For example, when standardizing to the classification code of the seventh edition of the international patent classification, among the documents stored in the document database, classification codes other than the seventh edition of the international patent classification are assigned to each type of classification code. Using a correspondence table (so-called concordance table) in between, for example, a document to which the classification code of the international patent classification 6th edition is given, is given while referring to the concordance table from the 6th edition to the 7th edition The existing classification code is converted into a seventh version classification code and registered in the document database.

  Further, as shown in FIG. 3, the storage unit 13 may hold a dictionary database in which a keyword is associated with a classification code to be assigned to a document related to the keyword. This dictionary database may be updated, for example, when a new document is added to the document database. This update process is executed by the control unit 11. The contents of this update process will be described later in detail.

  The operation unit 14 is a mouse, a keyboard, or the like, and outputs the content of the user's instruction operation to the control unit 11. The display unit 15 is a display or the like, and presents information to the user in accordance with an instruction input from the control unit 11.

  Here, the content of the process performed by the control part 11 is demonstrated. First, the control unit 11 accepts an input of text as a search condition from the operation unit 14. And the control part 11 extracts a keyword from the input text. Here, the keyword is a character string serving as a key for searching for a document in the document database. Specifically, the control unit 11 divides the text that is the search condition by a subject-predicate-related unit (generally a unit larger than a word), and stores each character string obtained as a result of the division in the storage unit 12 as a keyword. . For example, in the case of Japanese, it may be separated by a particle (case particle / corresponding particle) such as so-called “Tenihaha”. Note that unnecessary particles and the like are removed from each of the character string groups obtained by the division. Further, an unnecessary word database in which unnecessary words (stop words) are listed in advance is held in the storage unit 13, and the listed unnecessary words are removed from the storage unit 12.

  For example, “The interior of the teapot is divided into two by extending the partition to the vicinity of the opening, and one spout is provided in each chamber obtained by dividing the partition into two tea bowls in one teapot. By dividing the text “Improved convenience so that it can be poured into”, a character string such as “teapot”, “inside”, etc. is obtained. Then, parts such as particles are removed, and “teapot”, “inside”, and so on. Next, character strings such as “inside” and “two minutes” are removed as predetermined unnecessary words (character strings that can appear in any document), and eventually “teapot” and “near the opening” , “Partition”, “each room”, “spout”, “tea pot”, “tea bowl”, “pour”, and the like. The control unit 11 selects these character string groups as keywords.

  Further, the control unit 11 may perform a process of extracting the keyword from the entire input text, but may select a part of the text as a target part and extract the keyword from the selected target part. Specifically, when the entire text of a patent specification (including claims) is input as the text of a search condition, a column of claims, a column describing an embodiment or an example is selectively set as a processing target. It is also possible to identify and extract a keyword from the identified portion to be processed.

  Note that here, keywords are extracted by dividing them in units of subject predicates, but after dividing each word by morphological analysis, for example, a character string obtained by concatenating adjacent kanji words May be extracted as a keyword. As a result, for example, a term such as “ultraviolet irradiation device” is divided into “ultraviolet light”, “irradiation”, and “device”. Documents related to what to do are included in the search results).

  Next, the control unit 11 searches for a classification code associated in advance with these extracted keywords. That is, the control unit 11 searches each keyword from the dictionary database. If a classification code (a plurality of classification codes) related to the keyword is stored in association with the dictionary database, the list of classification codes is stored in the storage unit 12 in association with the keyword. At this time, when a part of the classification code is registered as an important code in the dictionary database, only the important code may be selectively extracted to form a classification code list.

  If the keyword is not stored in the dictionary database as a result of the search (if there is no classification code associated with the keyword), processing for extracting a document group is performed for the keyword. That is, the control unit 11 extracts a document group related to each extracted keyword from the document database by a full-text search process or the like. Thereby, for each keyword, a document including each keyword is extracted from the document database.

  The control unit 11 extracts at least a part of the classification code assigned to each of the documents extracted by this search. For example, when a plurality of classification codes are assigned to the document, the first one is taken out.

  The control unit 11 obtains a list of classification codes for each keyword by this process, and stores each list in the storage unit 12 in association with the keyword. Specifically, as in the above example, each result of “teapot”, “near the opening”, “partition”, “each room”, “spout”, “teapot”, “tea bowl”, “pour” As shown in Fig. 4, a list containing "A23F 3/06", "A45C 11/20", etc. of the seventh edition of the international patent classification is stored for "teapot" as shown in Fig. 4 A list including “A11C 11/02” and the like is stored. This list is illustrated as including overlapping classification codes, but after sorting in a predetermined order such as alphabetical order, the process of removing duplicate lines (UNIX ( (Registered trademark) command, processing equivalent to the uniq command) may be performed. This makes it possible to generate a list excluding duplicates.

  Then, the control unit 11 registers the keyword obtained here and a list of classification codes related thereto in the dictionary database. As a result, a list of classification codes for keywords that have not been registered in the dictionary database can be registered in the dictionary database. That is, it can be said that the dictionary database is a cache of the result of the classification code list generation process of the control unit 11.

  Note that at least one of the classification codes included in the list of classification codes may be registered as an important code so as to be distinguishable from other classification codes. Specifically, before removing duplicates, the appearance frequency of each classification code is checked, and those whose appearance frequency is equal to or higher than a predetermined threshold are registered as important codes. Further, the control unit 11 may register a more specific classification code as an important code among the classification codes whose appearance frequency is equal to or higher than a predetermined threshold. Here, the specificity means a classification code that cannot be obtained from the result of searching the document database using another keyword as a key (even if it is obtained, the appearance frequency is less than a predetermined frequency).

  The control unit 11 refers to the results obtained by the search process and the classification code list generation process, and extracts the classification codes that exist between the keywords. Specifically, for each keyword, the control unit 11 generates a check table in which the column of the classification code obtained thereby is checked (FIG. 5). In FIG. 5, a symbol “◯” is shown in the checked column. After generating the check table, the control unit 11 next checks the number of checks for each classification code. For example, when there are five related keywords for a specific classification code, five checks are made in the column of the classification code on the check table.

  Then, the control unit 11 selects at least one classification code having the highest number of checks as the first key candidate classification code. Specifically, as in the above example, each result of “teapot”, “near the opening”, “partition”, “each room”, “spout”, “teapot”, “tea bowl”, “pour” If there is, the “A47G 19/22” is obtained with the classification code of the 7th edition of the international patent classification as corresponding to five of these seven keywords (excluding duplication).

  Here, the classification code having the largest number of checks is selected. However, for example, a condition that there are more checks than a predetermined ratio compared to the number of keywords, a predetermined threshold value, and the like. The first key candidate classification code may be selected under conditions such as those with the above number of checks.

  For example, under the condition that there is a check of a ratio of 50% or more, 50% of 7 keywords, that is, "3.5" or more (however, since the number is always an integer, "4" or more In other words, “A47J 31/06” corresponding to the four keywords is obtained.

  Further, the control unit 11 selects a part of the keywords extracted from the text input as the search condition as the central concept word, and selects the second key candidate classification code based on the central concept word. Here, the central concept word is a keyword that characterizes the content of the text, and is selected based on a predetermined condition from the keywords extracted by the keyword extraction process.

  Here, the predetermined condition is, for example, as follows. That is, the control unit 11 reads out a list of classification codes obtained by the search process and the classification code list generation process from the storage unit 12, and generates a logical sum of a set of classification codes included in the list. Thereby, a group of classification codes extracted in association with the extracted keyword is obtained. For each keyword, the control unit 11 calculates a ratio (classification code distribution ratio) that the number of classification codes extracted in association with the keyword occupies with respect to the number of classification codes included in the generated logical sum. For example, when the number of classification codes included in the logical sum is 100 and the number of classification codes obtained in association with the keyword “teapot” is 30, the classification code distribution ratio is 30%.

  The control unit 11 further examines the appearance frequency of each keyword from the extracted keyword group (the group before elimination of duplication). Specifically, as in the above example, each result of “teapot”, “near the opening”, “partition”, “each room”, “spout”, “teapot”, “tea bowl”, “pouring” If there is, the frequency is “2” for “teapot” and the frequency is “1” for other keywords. Therefore, the control unit 11 selects a keyword of interest in the order of appearance frequency, and checks whether or not the classification code distribution ratio calculated for the keyword of interest is below a predetermined ratio threshold (for example, 40%). Here, if it is below the predetermined ratio threshold value, the attention keyword is selected as the central concept word. If the ratio threshold value is not below, the next keyword of interest is selected. Note that a keyword whose appearance frequency is smaller than the predetermined frequency threshold in the keyword group may not be selected as a keyword of interest.

  Here, “teapot”, which has the highest frequency, is the keyword of interest, and the classification code distribution ratio for the “teapot” is 30%, so that 30% is below the predetermined ratio threshold. For example, this “teapot” is selected as a central concept word.

  Note that the control unit 11 may not select the central concept word and not select the second key candidate classification code based on the central concept word if there is nothing that matches the condition. Moreover, the number of central concept words is not necessarily one.

  The control unit 11 calculates the appearance frequency of each classification code appearing on the classification code list from the classification code list obtained for the central concept word. Then, a classification code whose appearance frequency exceeds a predetermined appearance ratio threshold value is selected as the second key candidate classification code. For example, in the classification code list obtained for the central concept word “teapot”, there are 85 classification codes, of which 35 (37.5%) are “A47G 19/14” and 24 (28%) Is “A47J 31/06”, and so on, if the appearance ratio threshold is set to 35%, “A47G 19/14” is selected as the second key candidate classification code.

  The control unit 11 further calculates a logical sum of the first key candidate classification code and the second key candidate classification code, and determines the result as a key classification code serving as a second search key. The control unit 11 searches a document associated with the determined key classification code from the document database. Then, information for identifying each document included in the document group (second document group of the present invention) obtained as a result of the search is displayed on the display unit 15.

  If the above flow is arranged, the control unit 11 performs an operation as shown in FIG. First, the control part 11 extracts a keyword from the text input as a search condition (S1). Then, for each extracted keyword, a list of classification codes assigned in advance to the document in the document database related to each keyword is acquired (S2). In the search of this process S2, for keywords that are cached and registered with a classification code list related to the dictionary database, the classification code list is obtained with reference to the dictionary database. The document database is searched using the keyword as a key, and as a result of the search, at least a part of the classification codes assigned to the documents included in the document group is extracted from the obtained document group, and the classification code list is obtained. .

  The control unit 11 checks how many keywords are associated with each classification code included in the list of classification codes acquired here. Then, for example, classification codes that are commonly associated with a predetermined number of keywords with respect to all keywords are extracted and used as a first key candidate classification code (corresponding to a list of classification codes for each keyword of the present invention). Select (S3).

  Next, the control unit 11 selects a central concept word from the keywords extracted in the process S1 (S4). The central concept word is selected according to the frequency of appearance of each keyword in the extracted keyword group and the distribution of classification codes extracted in relation to each keyword (related to each keyword in the logical sum of the classification code list). This is performed according to a predetermined rule based on the ratio of the extracted classification code.

  Then, from the classification code list for the central concept word, based on the appearance frequency, for example, a classification code having an appearance frequency exceeding a predetermined appearance ratio threshold is a second key candidate classification code (corresponding to the second list of the present invention). ) Is selected (S5). In this process S5, if there is no classification code exceeding the appearance ratio threshold value, the second key candidate classification code need not necessarily be selected.

  The control unit 11 further calculates a logical sum of the first key candidate classification code selected in the process S3 and the second key candidate classification code selected in the process S5, and obtains a key classification code based on the result ( S6). The control unit 11 searches the document database for a document related to the key classification code (S7), displays the search result on the display unit 15 and presents it to the user (S8), and ends the process.

  Next, dictionary database update processing by the control unit 11 will be described. When a new document is added to the document database, the control unit 11 may perform the following process as the dictionary database update process.

  That is, the control unit 11 generates a list of keywords already registered in the dictionary database. Then, each keyword included in the list is sequentially selected as a key, and the document database is searched using the selected key. Then, a document including the selected key is extracted from the document database. At least a part of the classification codes associated with the extracted document is taken out, a classification code list is generated, the keyword selected as a key is associated with the generated classification code list, and stored in the dictionary database. Store. The existing information stored in association with the keyword is overwritten. Thereby, the dictionary database is updated.

  The control unit 11 may further perform a process of presenting search keyword candidates. In this case, for example, the classification code database that stores the classification code and the character string related to the classification code in association with each other is stored in a storage that can be read by the control unit 11 such as the storage unit 13. This classification code database is, for example, an electronic version of the same one described in the classification table of the international patent classification.

  The control unit 11 retrieves the character string related to the key classification code obtained in the process S6 from the classification code database, displays the character string obtained by the retrieval on the display unit 15, and presents it to the user. .

  In this case, when the classification code is designed hierarchically (for example, “A01B 1/00” (manual work tool (grass edge cutting tool A01G3 / 06)) as in International Patent Classification, “ A01B 1/02 "(when designed to include 鋤; excavator, etc.) is also presented with a character string related to the classification code corresponding to the higher rank of the key classification code obtained in process S6. Also good.

  That is, in the international patent classification, when the key classification code is “A01B 1/02” and the character string obtained thereby is “鋤, excavator”, the classification code “A01B 1/00” which is the higher rank of the key classification code. The character string “hand tool” related to “is also presented.

  The control unit 11 displays a list of character strings associated with the key classification codes (and classification codes having a predetermined relationship with the key classification codes, such as higher ranks). When displaying this list, the documents are narrowed and searched by keyword search using the character string as a keyword from the document group (second document group of the present invention) included in the search result presented in step S8. The results (such as the number of documents obtained by the search) may be presented together. At this time, a button such as “designate” is displayed in association with each character string, and when this button is clicked, the above-described refined search is performed using the character string associated with the clicked button. As a result, a list of documents obtained may be presented.

  According to the present embodiment, it is possible to assist the selection of a classification code as a search key, and to easily search for a document.

  In the above description, the document database is described as a database in which publications related to Japanese patent applications are accumulated. However, after the key classification code is obtained, other documents having a classification code search index are obtained. You can also search the document database. For example, if the storage unit 13 stores a first document database that stores publications related to Japanese patent applications and a second document database that stores publications related to US patent applications, the following processing is performed. It can also be done.

  That is, the control unit 11 executes the processes S1 to S6 shown in FIG. 6 as they are. Here, when the list of classification codes is acquired in the process S2 or the like, the list of classification codes is acquired with reference to a document database (here, the first document database) in the same language as the text input as the search condition. In step S7, a document related to the key classification code is searched from at least one of the first and second document databases.

  In other words, in this embodiment, if a search condition is input in Japanese, a key classification code corresponding to the search condition is generated. If this key classification code is used, a document written in English, etc. Even for documents other than the above, the search processing can be easily performed only by creating a search index with the corresponding classification code.

  Here, for example, when the language of the text input as a search condition can be determined (a predetermined feature word may be used, or the user may input which language is used), it is used for describing a document. The document database may be divided for each language, and when the classification code related to the text input as the search condition is acquired, the document database related to the language of the determined search condition may be selectively referred to. .

It is a block diagram showing the example of a structure of the document search device concerning embodiment of this invention. It is explanatory drawing showing the example of the content of a document database. It is explanatory drawing showing the example of the content of a dictionary database. It is explanatory drawing showing the example of the list | wrist of the classification code for every keyword. It is explanatory drawing showing an example of a check table. It is a flowchart figure showing the process example of the document search device concerning an embodiment of the invention.

Explanation of symbols

11 control unit, 12 storage unit, 13 storage unit, 14 operation unit, 15 display unit.

Claims (9)

A document search apparatus that is connected to a document database that holds a plurality of documents associated with a classification code, and that searches a document that satisfies a given search condition from the document database,
A means of accepting text input as search criteria,
Keyword extracting means for extracting at least one character string as a keyword from the text as a first search key;
A first document group related to each of the extracted keywords is extracted from the document database, the first document group extracted for each keyword is referred to, and at least one of classification codes associated with the first document group is extracted. A list acquisition means for acquiring a list of classification codes for each keyword generated using the unit;
Determining means for determining a key classification code to be a second search key using the classification code list for each keyword;
Search means for obtaining a second document group related to the key classification code from the document database using the key classification code determined by the determination means;
With
The document search apparatus, wherein the second document group is presented as a search result. A first document database holding a plurality of documents associated with a classification code and a second document database having a search index for the classification code are connected to be accessible, and the first and second document databases A document search device for searching for a document satisfying a given search condition,
A means of accepting text input as search criteria,
Keyword extracting means for extracting at least one character string as a keyword from the text as a first search key;
A first document group related to each of the extracted keywords is extracted from the first document database, the first document group extracted for each keyword is referenced, and a classification code associated with the first document group is extracted. List acquisition means for acquiring a list of classification codes for each keyword, generated using at least a part of the keyword;
Determining means for determining a key classification code to be a second search key using the classification code list for each keyword;
Search means for obtaining a second document group related to the key classification code from the first or second document database using the key classification code determined by the determination means;
With
The document search apparatus, wherein the second document group is presented as a search result. The document search device according to claim 1 or 2,
A classification code and a classification code database that holds and associates a character string related to the classification code are connected to be accessible,
A document search apparatus, further comprising: a presentation unit that acquires a character string related to the key classification code determined by the determination unit from the classification code database and presents the acquired character string. The document search device according to any one of claims 1 to 3,
Based on the keyword extracted from the text, a central concept word related to the content of the input text is acquired, at least a part of the classification code related to the central concept word is acquired, and the classification code for each keyword is obtained. A second list generating means for generating a second list;
The document search device, wherein the determining means determines a key classification code as a second search key by using a list of classification codes for each keyword and a second list. The document search device according to claim 4,
A document search apparatus, wherein at least a part of the extracted keywords is selected according to a predetermined rule, and the selected keywords are acquired as central concept words related to the contents of input text. A document search method for searching a document satisfying a given search condition from a document database using a computer connected to a document database holding a plurality of documents associated with a classification code,
Accept text input as search criteria,
Extracting at least one character string as a keyword from the text as a first search key;
A first document group related to each of the extracted keywords is extracted from the document database, the first document group extracted for each keyword is referred to, and at least one of classification codes associated with the first document group is extracted. A list of classification codes for each keyword, generated using
Using the list of classification codes for each keyword, determine a key classification code as a second search key;
Using the determined key classification code, a second document group related to the key classification code is acquired from the document database,
The document search method, wherein the second document group is presented as a search result. Using a computer connected to a first document database holding a plurality of documents associated with a classification code and a second document database having a search index of the classification code, the first or second A document search method for searching a document that satisfies a given search condition from a document database,
Accept text input as search criteria,
Extracting at least one character string as a keyword from the text as a first search key;
A first document group related to each of the extracted keywords is extracted from the first document database, the first document group extracted for each keyword is referenced, and the classification code associated with the first document group A list of classification codes for each keyword generated using at least a part of
Using the list of classification codes for each keyword, determine a key classification code as a second search key;
Using the key classification code determined by the determining means, obtaining a second document group related to the key classification code from the first or second document database,
The document search method, wherein the second document group is presented as a search result. A document search program for causing a computer connected to a document database holding a plurality of documents associated with a classification code to search for a document satisfying a given search condition from the document database,
Accepting text input as search criteria,
A procedure for extracting at least one character string as a keyword from the text as a first search key;
A first document group related to each of the extracted keywords is extracted from the document database, the first document group extracted for each keyword is referred to, and at least one of classification codes associated with the first document group is extracted. A procedure for obtaining a list of classification codes for each keyword generated using
Using the list of classification codes for each keyword to determine a key classification code to be a second search key;
Using the determined key classification code to obtain a second document group related to the key classification code from the document database;
To the computer,
A document search program, wherein the second document group is presented as a search result. A first document database holding a plurality of documents associated with a classification code, and a second document database having a search index for the classification code, and a computer connected to the first or second document database; From which a document satisfying a given search condition is searched,
Accepting text input as search criteria,
A procedure for extracting at least one character string as a keyword from the text as a first search key;
A first document group related to each of the extracted keywords is extracted from the first document database, the first document group extracted for each keyword is referenced, and the classification code associated with the first document group Obtaining a list of classification codes for each keyword generated using at least a part of
Using the list of classification codes for each keyword to determine a key classification code to be a second search key;
Using a key classification code determined by the determining means to obtain a second document group related to the key classification code from the first or second document database,
A document search program, wherein the second document group is presented as a search result.

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