JPH03131970A - document search device - Google Patents

Abstract

PURPOSE:To select a proper keyword and to easily form a retrieving condition expression by displaying relational keywords in the descending order of accuracy of keywords at the time of forming a user's retrieving condition expression. CONSTITUTION:The user calculates the keyword accuracy of all keywords by a keyword accuracy calculation part 16 at the time of forming a retrieving condition expression and displays a series of keywords rearranged in the descending order of keyword accuracy by a keyword sorting part 17 on a display part 19. Thereby, the user can select a proper keyword out of the series of displayed keywords and complete the retrieval condition expression.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a document retrieval device, and particularly to a document retrieval device, which can generate a group of keywords that are close to the sense of the user during a search, and furthermore, the closer the search results are to the user's search request, the more the search results are searchable. The present invention relates to a flexible and high-speed document retrieval device that can be ordered by evaluation values having large values.

2. Description of the Related Art In conventional document retrieval devices, when registering a document, a registration operator has to select keywords deemed appropriate, classify them appropriately using a thesaurus, and update the thesaurus as keywords are added or deleted, which is quite a complicated task. Furthermore, in order to search for documents that generally satisfy the search conditions specified by the user during a search, it is necessary to reconsider the search conditions and perform the search again.

In order to solve these problems, we use keyword connections, which are related information between keywords, and introduce an evaluation value called document accuracy, which has a larger value when searching for documents, as the closer it is to the user's search request. A document retrieval device that allows a user to flexibly search for documents that meet his/her requirements has been proposed by the present applicant in Japanese Patent Application No. 8291/1983. Furthermore, a system with a learning function that changes the weight of each keyword connection based on the user's judgment and instructions and reflects that judgment in the search results at the next search was proposed in Japanese Patent Application No. 1979-197988. ing. Furthermore, we have improved the document accuracy so that it can be calculated for search expressions in which multiple keywords are combined using any combination of AND, logical OR, and negation operators as document search conditions for users. Devices with a learning function have also been proposed.

Problems to be Solved by the Invention In a series of proposals using such keyword connections, keywords are sorted in an appropriate order (i.e., numerical values representing appropriateness evaluations are sorted by keyword accuracy) in order to support users' search condition expressions. A function to display the information to the user has also been proposed. However, it is for a group of search keywords, and AND (logical product) and OR (
The method for calculating keyword accuracy when there is a logical operator such as (or) has not been considered.

Therefore, creating a search condition expression is troublesome and inconvenient.

Means for Solving the Problems Keyword extraction means for extracting keywords from the registered document when registering a registered document and its bibliographic information in a document database; and an inverter that indicates the relationship between the registered document and the keyword. an inverted file creation means for creating an inverted file, and a keyword connection table processing means for creating a keyword connection table that describes related information between the keywords, and modifying already registered related information to generate new related information. A value indicating the strength of the relationship between the keywords included in the search condition expression, which is a combination of keywords and logical operators input by the user, and the keyword group of registered documents in each file is defined as document certainty. document accuracy calculation means for defining and calculating document accuracy using the keyword connection table, the inverted file, and a predetermined method; and a document sorting unit for outputting search result documents in order of the calculated document accuracy.
a display management means; a learning management means for changing the weight of a keyword connection according to a predetermined method when a user interactively instructs whether or not the document accuracy given to each document in the search results is appropriate; a keyword accuracy calculation means that defines keyword accuracy as a value indicating the strength of association between a search condition expression input by a person and each keyword, and calculates keyword accuracy using a predetermined calculation formula; a keyword sorting means for outputting keywords in order of size; and a document selection means for selecting documents that match the search condition expression; Keywords are now displayed in order of relevance in the search condition formula based on the keyword accuracy calculated for all keywords.

Effect When a user creates a search condition expression, keywords related to the search condition expression being created are displayed in descending order of keyword probability, so the user can select an appropriate keyword from the displayed set of keywords. If possible, keyword selection will be supported, making it easier to create search condition expressions that include logical operators, and making it possible to perform appropriate document searches.

Example An embodiment of the present invention will be described based on the drawings.

First, the document retrieval device of the present invention is premised on the use of the concept of keyword connection, similar to the previously proposed method described above. In addition, we have introduced the concept of evaluation value called document accuracy, which has a larger value for each document as it is closer to the user's search request, and when searching for a document, the user can search for documents that satisfy the user's request based on the degree of document accuracy. This allows for flexible selection. A keyword connection is a description of a relationship between keywords.

Specifically, in the keyword connection of this embodiment, the magnitude of the relationship is set in a range from 0 to 1, where 0 indicates that there is no relationship between the keywords, and a value of 0 or more indicates that there is a relationship, especially l indicates the magnitude of the relationship. is the maximum.

Related information between the i-th keyword and the third keyword (hereinafter referred to as "weight J") can be expressed as Wij.

Based on the second assumption, the document search device of the present invention is configured as shown in the drawings. First, when the keyword extraction unit 1 inputs the registered document 2, it extracts keywords from the document, and sends the keywords and the registered document 2 to the document information management unit 3, the keyword connection table processing unit 4, and the inverted file creation unit 5. This is what is output. Document information management department 3
stores keywords and bibliographic information 6 in file 7,
It creates a database in a format that can be used when searching. The keyword connection table processing unit 4 creates a keyword connection table that describes related information between keywords and stores it in a file 8. Furthermore, if there is a request from the learning management section 9, the weight of the keyword connection is changed.

The inverted file creation section 5 creates an inverted file showing the relationship between keywords and registered documents, and stores it in the file 10.

The document selection section 11 includes the learning management section 9 and the document accuracy calculation section L.
2. It consists of a request processing section 13, a document sorting section 14, a display management section 15, a keyword certainty calculation section 16, and a keyword sorting section 17. First, the document accuracy calculation unit 12 uses the necessary information in the keyword connection table stored in the file 8 to calculate the document accuracy for each document based on the search condition expression consisting of keywords transferred from the request processing unit 13. Calculate. This calculation power formula will be described later.

The document sorting unit 14 sorts all the documents stored in the file 7 in descending order of document accuracy calculated by the document accuracy calculation unit 12, and transfers the sorted documents to the display management unit 15. Request processing unit 1
3 transfers the search condition expression entered by the user from the keyboard 18 to the document certainty calculation section 12. Further, when displaying search results on the display 19, a display instruction input by the user is transferred to the display management section 15. Furthermore, if there is an instruction from the user, information regarding learning of keyword connections is transferred to the learning management section 9. The learning management unit 9 performs keyword connection learning according to the user's instructions given from the request processing unit 13. That is, the learning management section 9 calculates the amount of change in each weight of the keyword connection, but the actual change in the weight value is performed by giving an instruction to the keyword connection table processing section 4. The learning method will be described later. The display management section 15 displays the search results on the display 19 according to the user's instructions given from the request processing section 13. The keyword accuracy calculation unit 16 is the request processing unit 13
The keyword accuracy calculation unit 17 calculates the keyword accuracy for each keyword using the necessary information in the keyword connection table stored in the file 8 according to the user's instructions given from the keyword connection table. All the keywords are sorted in descending order of keyword accuracy and transferred to the display management section 15.

The purpose of the document search process is to search and display appropriate documents according to the user's request, and document selection processing for this purpose is performed by the document selection unit 11.

Here, the search conditions are determined by specifying keywords and setting conditions for other bibliographic information.

First, it is determined whether condition settings other than keywords for each document are satisfied. If the conditions are met,
The document accuracy of the document is calculated as described below. If the conditions are not met, the document accuracy of the document is not calculated and the value is set to O.

Keywords are specified using a search condition expression consisting of keywords that express the information the user wants to obtain. A search condition expression is a keyword or multiple keywords.
They are combined using D (logical product), OR (logical sum), and NOT (negation).

A combination of multiple keywords is used when a single keyword expressing the information the user is trying to obtain does not exist in the document management device.

Next, the search condition expression, document accuracy calculation method, and keyword connection learning method included in the previously proposed contents will be individually explained.

A. Search condition expression The search condition expression that the main document search device accepts as input is:
Keywords are AND (logical product), OR (logical sum), N
They are connected using the OT (negation) operator. As a result, it is possible to search for, for example, ``Document J without keyword A'' ``Document with both keywords A and B''. A search condition expression in which keywords are arbitrarily combined with AND, OR, and NOT can be converted into a product standard form in which a sub-search condition expression in which keywords are combined with OR and NOT is combined with AND. This conversion is performed by the request processing unit 13. The search condition expression for the product standard form is: Query = SQ(1)*・------* 5Q(
N) ・---Represented by (1). +1 here
*II represents AND and is Na3. Also, 5Q
(h) represents the sub-search condition expression % expression % (2) which is made up of only OR and NOT. Here, "l K q, II represents the Q+th keyword, ll + II represents OR, "j" represents NOT, and n≧O, m≧1, n+m≧1. A set of keywords that cannot be negated. Let Q+(h) be Q+(h), and let Q-(h) be the set of keywords with negation, then Q”(h) = (Kq, , −・−= , Kq
,)Q-(h) = (Kq,,+1,...
......, Kqn+,, ). However, Q
It is assumed that there are no keywords included in "(h), Q'lh) at the same time. This check is performed by the request processing unit 13,
If there are keywords included at the same time, a message to that effect is displayed on the display 19 to alert the user.

B1 Document accuracy calculation method Document accuracy is defined as a numerical value indicating the strength of the relationship between the keyword group of each document in the document database and the keyword in the search condition formula specified by the user. Calculated in section 12.

Document accuracy is determined in the following two steps.

a. Calculate the document accuracy for the sub-search condition expression (this is called sub-document accuracy).

b. Calculate the product of the sub-document accuracy for the full-open search conditional expression and use it as the document accuracy.

Document accuracy is calculated for all documents, appropriate documents are selected by threshold processing, etc. according to the user's specifications, and search results are obtained.

The above two steps will be explained. First, the first step is to calculate the subdocument probability for the subsearch condition expression.
Letting the h-th subdocument accuracy be ri(h), the following (3)
It is carried out according to the formula.

However, when Ai is a set of keywords indexed to the first document, Rlj and SiJ are calculated by the following equations (4) and (5).

However, Wjk indicates the degree of association between the j-th keyword and the j-th keyword.

If Q+(h) or Qlh) is an empty set (φ), then (
The following equations (6) and (7) are used instead of equation 3).

jfEQ-(h) As a second step, after calculating all sub-document probabilities for N sub-search condition expressions, document probabilities are calculated using equation (8).

ri = +1 ri(h)...
(8) C. Keyword connection learning method Keyword connection learning is performed in the learning management section 9. As the keyword connection learning method, for example, the learning method described in Japanese Patent Application No. 1-132696 proposed by the present applicant is used.

That is, the user's judgment regarding the search result during learning is assigned "l" if the answer is correct, "0" if it is incorrect, and an ambiguous judgment is expressed as a real value between [0, l]. Letting L be the 3·V value representing the user's judgment regarding the document accuracy X, the evaluation function is defined as follows.

In one learning session, the document you are currently focusing on (here, i
All weights of the keyword connections are changed so as to reduce the value e(ri) of the document accuracy evaluation function for the document (denoted as the th document). That is, Wmn 1g(Wmn + aΔWmn) −
・--(to). Here, a is a learning coefficient of a positive real number, and g is a normalization function so that the value of the keyword connection after the change falls within the range of [0°1].

・・・・・・・・・・・・・・・・・・・・・・・・(1
1) Using the steepest descent method, the variation ΔWmn can be calculated as shown in equation (12).

・・・・・・・・・・・・・・・・・・(12) Here, from equation (8), therefore, ・・・・・・・・・・・・・・・・・・・・・・・・(
I4) In the calculation formula (14) for calculating the change ΔWmn, a r i (h)/a Wmn is (+
5) Calculated by equations (17). Therefore, m E Q ery is nEAi (m,
Since △Wmn=0 for combinations other than n), △Wm
It is necessary to calculate n by m EE Que
'J and nEAi are the only combinations of (m, n).

In order to calculate ΔWmn, it is necessary to calculate the partial differential of rt(h) with respect to Wmn. Here, Q” (
Based on the assumption that there are no keywords included in h) and Q-(h) at the same time, the partial differential of ri(h) with respect to Wmn can be calculated in the following three cases.

1. In the case of mEQ" (h)... (15) In the case of 2゜ mEQ"' (h)...・(16)
In the case of 3゜m1EQ” (h) or m cow Q-(h) (15) ~
By substituting the result calculated by equation (17) into equation (I4), ΔWmn can be obtained, but equation (14) can be further simplified.

In that case, Depending on whether i=0 or not Since the calculation formula is different, In the following, we divide into two cases. I will explain.

■.

If i≠O At this time, all h (l≦h≦N) against Since i (h)≠O, From equation (8) Since it can be rewritten as Equation (13) is as follows become.

Therefore, ・・・・・・・・・・・・・・・・・・・・・・・・(
20) ■.

If 1=00 When i=0, The number of h such that 1(h)=0 The calculation formula changes.

If the number of h is 1, then If h is h*, then Equation (13) becomes as follows.

Therefore, ・・・・・・・・・・・・・・・・・・・・・・・・(
22) When the number of h is two or more, equation (13) becomes as follows.

Therefore, ΔWmn = O・・・・・・・・・・・・・・・・
(24) Now, a description will be given of the time when a user creates a search condition expression, which is a feature of this embodiment.

When performing a search, a user creates a search condition expression by appropriately combining keywords and logical operators. In this embodiment, in order to select an appropriate keyword at this time, keywords related to the search condition expression being created are displayed on the display 19 to assist in the creation of the search condition expression. Specifically, the keyword accuracy calculation unit 16 calculates the keyword accuracy for all keywords, and the keyword sorting unit 17 presents the user with a series of keywords sorted in descending order of keyword accuracy. Here, the keyword accuracy refers to a numerical value representing the magnitude of the relationship between the search condition formula (currently being created) manually entered by the user and each keyword. Therefore, the user can select an appropriate keyword from the displayed series of keywords (keyword accuracy is easy) and complete the search condition expression.

Here, a method for calculating keyword accuracy will be explained.

Now, if Ti(h) is the keyword certainty for the first keyword for the h-th sub-search condition expression, its value is calculated by the following equation.

・・・・・・・・・・・・・・・・・・・・・・・・
(25) Furthermore, the final keyword accuracy Ti is calculated by the following formula.

Effects of the Invention Since the present invention is configured as described above, when a user creates a search condition expression, keywords related to the search condition expression that is being created are displayed in descending order of keyword accuracy, thereby supporting keyword selection. This allows users to select appropriate keywords from a displayed set of keywords, making it easy to create search condition expressions using keywords and logical operators, and enabling appropriate document searches. be.

[Brief explanation of the drawing]

The drawing is a block diagram showing one embodiment of the present invention. l...Keyword extraction means, 2...Registered document, 4.
...Keyword connection table processing means, 5.Inverted file creation means, 9.Learning management means,
11... Document selection means, 12... Document accuracy calculation means, 14... Sorting means, 15... Display management means, 1
6...Keyword accuracy calculation means, 17...Keyword sorting means

Claims (1)

[Claims] Keyword extraction means for extracting keywords from the registered document when registering the registered document and its bibliographic information in a document database; and an inverted file for creating an inverted file indicating the relationship between the registered document and the keyword. A keyword connection table processing means is provided for creating a keyword connection table that describes related information between the keywords, modifying related information that has already been registered, and generating new related information. A value indicating the strength of the relationship between the keyword included in the search condition expression based on the combination of the input keyword and logical operator and the keyword group of the registered documents in each file is defined as the document certainty, and the keyword connection is A document accuracy calculation means that calculates document accuracy using a table, an inverted file, and a predetermined method, and a document sorter that outputs search result documents in the order of the calculated document accuracy.
a display management means; a learning management means for changing the weight of a keyword connection according to a predetermined method when a user interactively instructs whether or not the document accuracy given to each document in the search results is appropriate; A keyword accuracy calculation means that defines keyword accuracy as a value indicating the strength of the relationship between the search condition expression input by the user and each keyword, and calculates the keyword accuracy using a predetermined calculation formula; and the calculated keyword accuracy. and a keyword sorting means for outputting keywords in order of magnitude of the search condition expression, and a document selection means for selecting documents that match the search condition expression. A document search device characterized in that keywords are displayed in descending order of relevance to a search condition expression based on keyword accuracy calculated for all keywords.