JPH086957A - Data retrieval device - Google Patents

Abstract

PURPOSE:To dynamically form a consistent context even in a large scale system by describing how to look a context and a link based upon keywords allocated to respective nodes and changing the context in accordance with a selected link. CONSTITUTION:A hypertext system 1 sets up nodes corresondingly to data to be managed by a media data managing parts 7A, 7B,... in a data base part 4 and links among nodes to form a network. A node information managing part 8 in the data base part 4 manages a node keyword set attribute describing a set of keywords added to respective nodes as an attribute value and a node link control rule attribute for regulating how to look links, describes a context by a set of keywords and regulates how to look respective links connected to the nodes by using a control sentence expressed by the link control rule attribute. The context is changed in accordance with a link selected by a reader.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data search device,
For example, it can be applied to a hypertext system.

[0002]

2. Description of the Related Art Conventionally, in a hypertext system, nodes are defined in correspondence with information such as text data, and these nodes are connected by links to form a network. As a result, the hypertext system can sequentially provide the information corresponding to the nodes to the reader by sequentially tracing the network and sequentially provide the information required by the reader.

In this hypertext system, the reader may be in a so-called stray state in which he is uncertain about his current position or the direction to proceed to while he is arbitrarily navigating through a complicated network of nodes. is there. In order to avoid this stray child effectively, it is necessary to control the navigation in consideration of the context of a series of information provided sequentially.

Further, in the hypertext system, the context formed by this series of information differs depending on how the network is traced. Therefore, the author of hypertext must manage which context allows which context. I won't. Moreover, not all of the routes are useful, only those that can provide only a semantically consistent context must be able to be provided.

As one of the conventional navigation control methods considering the above points, a file is formed for each user (reader or author), and a link corresponding to each user is created in the file (web). Is described (Chapter 5 of the following document). As a result, this kind of hypertext system describes how to trace the network in a file for each user, effectively avoids the stray state based on this file, and also semantically corresponds to the degree of understanding of the user. It is designed to form a consistent context.

[0006] Further, there is also a system in which a node is represented by one line in place of this web to form a network, and this network is defined as a guided tour (Chapter 8 of the following document). This hypertext system defines the nodes to be shown to the reader and their linear order for each reader according to the degree of the reader by controlling the navigation based on the guided tour. By clicking the icon labeled "node", it is possible to effectively avoid the stray state and provide necessary information to each reader in sequence. That is, this method succeeds in giving a fixed context, and by defining a plurality of guided tours using the same node, the reader can navigate in some contexts.

Reference: J. Nielsen, “Hyper Text & Hyp
Published by Academic Press Inc. (Translated by Takashi Saito, published by HBJ Publishing Bureau in 1991)

[0008]

However, in the case of providing text data or the like on the basis of a preset web or guided tour as described above, the network can be followed only by the route set by the author in advance, which is fixed. There is a problem that the context can be defined only in a limited way.

Therefore, in the conventional hypertext system, even if the number of navigable contexts exponentially increases due to the large scale and complexity of the network, all of them cannot be described, and the reader eventually selects them. Due to the small number of contexts obtained, there is a drawback that the possibility of large-scale and complicated networks cannot be fully utilized. Further, in this case, it may be possible that the desired data required cannot be retrieved.
Due to the small number of contexts that the reader can choose from, it is possible to provide unneeded readers with unnecessarily basic matters or, conversely, to less understood readers with difficult or specialized matters. May be provided. Since the reader originally decides the link to go to next depending on his / her understanding, it is against the purpose of hypertext to set the fixed context.

Such a problem similarly occurs not only in the hypertext system, but also in other database systems having a large amount of prepared data.

[0011]

In order to solve the above-mentioned problems, the present invention forms a network with a plurality of nodes defined corresponding to a plurality of data and a link connecting the plurality of nodes. In a data search device that traces and provides data corresponding to a node, a data storage unit that stores data, a keyword storage unit that stores a keyword of data corresponding to a node, and a view of a link extending from each node, A link description means for describing each link on the basis of a keyword, a context description means for describing a context formed by tracing a network on the basis of a set of keywords, and a link when a node is traced on the network. Search for the description method, and select from the links extending from the visited node based on the context and the appearance of the link. Detecting a link is allowed to visit Te, with visits subsequent node by following the detected links, searching for keywords storage means and context description means,
A navigation control means for updating the context in accordance with a link connected to a subsequently visited node and recording it in the context description means.

[0012]

[Function] Assign keywords to nodes corresponding to data, and see how links extend from each node.
Describe each link based on the keyword, describe the context formed by tracing the network based on the set of keywords, and extend from the visited node based on the context and the appearance of the link. If a link that can be subsequently visited is detected from among the links, it is possible to easily and dynamically form a large amount of contexts.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a hypertext system will be described in detail below. Here, FIG.
2 is a block diagram showing the configuration of this system, and FIG.
6 is a flowchart showing the processing of the hypertext control unit.

In FIG. 1, the hypertext system 1 of this embodiment comprises a display unit 2, an input unit 3, a database unit 4, a user interface management unit 5 and a hypertext control unit 6. In this hypertext system 1, users (authors and / or readers)
Operates the input unit 3 formed of a keyboard, a mouse, etc. while monitoring the display of the display unit 2 to build a database in the database unit 4 and retrieve necessary information from the database unit 4 for the user. It is provided.

Therefore, the hypertext system 1 is
The user interface management unit 5 receives commands for navigation of hypertext, window control commands, etc. obtained from the input unit 3, and outputs these commands to the hypertext control unit 6. Further, the hypertext system 1 receives the display data such as the content of the node output from the hypertext control unit 6 in the user interface management unit 5, and drives the display unit 2 according to this display data.

The database unit 4 has a plurality of media data management units 7A, 7B, ..., In each of the media data management units 7A, 7B, ..., Text data, image data, moving image data, still image data, voice data, respectively. Manage data according to media such as data. The hypertext system 1 uses these media data management units 7A,
The nodes are set corresponding to the data managed by 7B, ... And the nodes are connected by links to form a network. By tracing this network, the data forming the database is sequentially arranged as necessary. It is designed to be offered to readers.

The database unit 4 includes a node information management unit 8
And a link information management unit 9, and the node information management unit 8 and the link information management unit 9 manage these media data management units 7A, 7B, ....

The node information management unit 8 manages information and attributes of each node. Information and attributes of managed nodes include a node identifier for identifying a node, a data identifier for identifying data held by the node, a link identifier for identifying a link connected to the node, and a link control of the node. These are rule attributes and node keyword set attributes.

Here, the keyword set attribute describes a set of keywords added to each node as an attribute value, and in the case of this embodiment, the authors appropriately express the contents of each node by these keywords. Input unit 3 in advance
Operate to set. A major feature of this embodiment is that the keyword set attribute is used for context navigation control as described later.

Further, the link control rule attribute of the node defines the appearance of the link, and is described as shown in the equation (1) for the number of links connected to each node. In the case of this embodiment, the author inputs in advance the input unit 3
Operate to set.

[0021]

[Equation 1] Here, the conditional expression is formed by a logical expression of a keyword. As a result, in this embodiment, the context is described by a keyword set, and when the context is assigned to this logical expression and a true logical operation result is obtained, the navigation of the reader about the link that obtains this true logical operation result is performed. It is designed to allow it.

As a result, in the hypertext system 1, the next visiting link is detected from the links connected to the node according to the context and the like that have been followed, and the information provided up to that point is detected. In contrast, the information that is subsequently provided is designed to form a semantically consistent context.

As described above, the hypertext system 1
In (1), the appearance of each link connected to a node is defined using a control statement represented by a link control rule attribute.

The action part in the link control rule attribute is formed by a list of node identifiers and context change expressions. This context change expression is formed by a set operation expression in which a keyword set is described as a union set and / or a difference set. In the case of this embodiment, this set operation expression is executed and a keyword and context assigned to each node are formed. By forming a union set with the set of keywords, the context set corresponding to the reader is sequentially changed while tracing the network.

The hypertext system 1 is designed to be able to easily navigate the network by describing these link control rules with attribute values, and the author sets the link control rule attributes for each link in advance. By this, the author predefines the appearance of the link. Further, the hypertext system 1 changes the context according to the set arithmetic expression and the keyword assigned to the node, and thereby updates the context according to the information provided to the reader.

As described above, in the hypertext system 1, information is provided so as to form a semantically consistent context with respect to the information provided so far,
Further, according to the information provided, the context is updated so that the subsequently provided information is semantically consistent.

Therefore, the hypertext system 1 is
By simply assigning a keyword to a node and assigning a control statement to a link corresponding to this keyword, a large amount of context that is semantically consistent can be formed for each reader.

The link information management unit 9 manages information about links between nodes, and identifies a link, a link identifier for identifying a link, an identifier of a node serving as a start point of the link, position information of data corresponding to the node identifier, and an end point of the link. And the position information of the data corresponding to this node identifier are managed. As a result, the hypertext system 1 can manage the history in the link information management unit 9.

The hypertext control unit 6 is formed of, for example, an arithmetic processing circuit, and executes the processing procedure shown in FIG. 2 to sequentially provide information required by the reader.

When the hypertext system 1 is activated by the activation command from the reader, the hypertext control unit 6 moves from step SP1 to step SP2, and after reading the initial setting file of the reader in response to the operation of the input unit 3. , Accept reader input commands. here,
Both the initialization file and the input command are formed by a set of keywords, and the hypertext control unit 6 sets the set formed by the initialization file and the input command as an initial context.

Subsequently, the hypertext control unit 6 moves to step SP3, and the author sets the node currently visited by the reader (hereinafter referred to as the current node) as the entrance of the hypertext navigation by the processing of step SP2. The node (hereinafter referred to as the home node) is set, and the history list showing the history of the navigation of the reader is set to the empty list.

When the preparation for the start of navigation is completed,
The hypertext control unit 6 moves to step SP4,
The keyword set of the current node (the attribute value of the keyword set attribute) is searched by searching the keyword set of the current node via the node information management unit 8 and the union of the searched keyword set and the keyword of the current context To the context up to the current node. Also,
In step SP4, the hypertext control unit 6 adds the identifier and context of the current node to the history list (when the process of step SP4 is executed for the first time, it adds the empty history list to the beginning of the history list). Will be recorded in step 3), and then step SP5
Move on to.

Here, the hypertext control unit 6 determines the media data management unit 7 based on the contents of the current node.
After searching the data of A, 7B, ..., The search result is displayed on the display unit 2 through the user interface management unit 5, and the reader is provided with the data of the database unit 4 corresponding to the current node.

Next, the hypertext control unit 6 moves to step SP6 and detects the link control rule attribute of the current node by detecting the link control rule attribute defined for the current node. Detects the appearance of the link set by.
Further, the hypertext control unit 6 collates the conditional expression and the keyword set of the context with respect to the link control rule detected in this way, and from this collation result, obtains a link control rule that yields a true operation result in the conditional expression. To detect. As a result, the hypertext control unit 6 defines the appearance of the link corresponding to the reader from the appearance of the link set by the author based on the context represented by the keyword set.

Subsequently, the hypertext control unit 6 proceeds to step SP7, extracts the link identifier corresponding to the link control rule for which the true calculation result is obtained, and outputs the link information corresponding to this link identifier to the link information management unit. Take out from 9. Further, the hypertext control unit 6 displays an anchor on the information of the current node currently displayed based on this link information.

Here, the anchor represents the starting point of the link. For example, when the data of the current node is text data, the character string corresponding to the anchor and the display color of the paragraph are changed from the character string of the displayed text data, and the character string corresponding to the anchor and the paragraph are highlighted. By displaying it, it is expressed that the link is coming out from these character strings and paragraphs, and these character strings,
By clicking the paragraph with the mouse, you can follow the links following this current node. Further, for example, when the data of the current node is a figure or a table, the display color is switched or highlighted for the anchor title, item, etc., and the link is displayed by switching the display color or highlighted for the entire node.

When the data of the current node and the anchor representing the link are displayed in this way, the hypertext control unit 6 moves to step 8 and waits for the reader's command input. Here, when the reader operates the keyboard or the mouse to input an end command, the hypertext control unit 6 moves to step SP9 to end this processing procedure, while the hypertext control unit 6 reads one of the displayed anchors. If is selected, the process proceeds to step SP10, and if backtrack is selected, the process proceeds to step SP11.

In step SP10, the hypertext control unit 6 described above about the selected link.
The processing of the operation part represented by the equation (1) is executed to generate a keyword set, and this keyword set is set as the keyword set of the current node (that is, in the context). Further, the hypertext control unit 6 detects the end node of the selected link and sets it as the current node, and then returns to step SP4 described above.

On the other hand, when the reader selects backtrack, the hypertext control unit 6 proceeds to step SP11 as described above, detects the previous element from the history list, and then defines this element. Return to the node that is played. That is, the previous context element is con and the node element is
If it is nid, the context is set to con and the current node is set to nid, and this element is deleted from the history list, thereby returning to the previous node, changing the history list and context, and returning to step SP5 described above. Return.

Next, navigation control of the hypertext system 1 will be described using a specific example.

(Specific Example 1) When a network is formed by links for which link control rules are not defined or links in which the link control rules are always set to be true, the reader always follows all links. And can form the most basic form of hypertext system.

(Specific Example 2) A network as shown in FIG. 3 in which nodes and links are represented by circles and arrows, respectively, will be described.

This network has a node identifier 1
5 to 5 and 6 links having link identifiers a to f. For each of the links (link identifiers a to f), link control rules represented by formulas (2) to (7) are defined as attributes. Also,
The link control rules of the links a and b are defined by the link control attribute of the node 1, the link control rules of the links c and d are defined by the link control attribute of the node 2, and the links e and f are defined.
The link control rule is defined by the link control attribute of node 3. Furthermore, it is assumed that an empty keyword set is assigned to all the nodes.

[0044]

[Equation 2] Further, as shown in the expressions (2) to (7), only the node identifier is assigned to the operation part of the link control rule, and the context change expression is not specified. As a result, of the processing procedures of step SP4 and step SP10 for changing the context, in this network, the context is changed only in step SP4, and at the time of this change, a keyword (keyword set) is defined in any node. Therefore, the keyword set assigned to the initial context is retained as it is.

In this network, soft is used as the initial context by the reader's initialization file or command input.
If ware is defined, hypertext system 1
Are conditional expressions (2), (4) ~ that match the initial context software.
By detecting the expression (6) and selecting the corresponding link, the reader can follow the nodes in the order of node identifier 1 → 2 → 3 → 4 or node identifier 1 → 2 → 4. That is, for the reader, as shown in FIG.
Link identifiers a and c to e are node identifiers 1 to 4
The node with the node identifier 5 is invisible, and the node with the node identifier 5 cannot be seen.

On the other hand, when hardware is set as the initial context in this network, equation (3) and
By obtaining the true operation result with the conditional expression of (7),
The links with link identifiers b and f are selected, and the reader can follow the nodes in the order of node identifiers 1 → 3 → 5,
To the reader, the appearance will be as shown in FIG.

According to the description method as in Example 2,
This hypertext system 1 can carry out navigation control in the same manner as when carrying out navigation control based on the web.

(Specific Example 3) Next, node identifiers 6 to 13
An example of the network shown in FIG. 6 that includes nodes represented by and links represented by link identifiers g to n will be described.

Link control rules represented by the equations (8) to (15) are defined as attributes for each link (link identifiers g, ..., N) in this network.
Here, the link control rule of the links g and h is defined by the link control attribute of the node 6, the link control rule of the links i and j is defined by the link control attribute of the node 7, and the link control rule of the link k is defined by the node 8. Is defined by the link control attribute of the node 9, the link control rule of the link 1 is defined by the link control attribute of the node 9, and the link control rules of the links m and n are defined by the link control attribute of the node 10.

[0050]

(Equation 3) In addition, also in the expressions (8) to (15), the context change expression is specified so as to obtain the union of the keyword set assigned to the node and the keyword set assigned to the initial context. Omit it.

The nodes with node identifiers 7, ..., 13 in this network are "history", "geography", "person", "clothes", "portrait", "person", and
The keyword "clothes" is defined. Also, conte
xt is a reserved word that represents the current context.

In this case, no matter which keyword is input as the initial context, when the node with the node identifier 6 is set as the current node, the conditional expressions in the expressions (8) and (9) are truly defined. Therefore, the hypertext system 1 displays the link identifiers g and h as anchors.

When the reader selects the anchor of the link identifier g in this state, the hypertext system 1 sets the keyword "history" in the context, and then sets the node of the subsequent node identifier 7 as the current node, and then (10). The link identifiers i and j are displayed as anchors from the expressions and (11). Here, when the reader selects the anchor of the link identifier i, the hypertext system 1 sets the keyword “history, person” in the context, and when the anchor of the link identifier j is selected, the hypertext system 1 sets the keyword “history, clothes”. Set in context. Furthermore, when the node of the node identifier 10 is reached via the node of the node identifier 8, the keyword “history, person, portrait” is set in the context, and when the node of the node identifier 10 is reached via the node of the node identifier 9, the keyword is set. Set "History, clothes, portraits" as context.

With this context setting, the hypertext system 1 gives the readers who follow the nodes in the order of the node identifiers 6 → 7 → 8 → 10 (the context is "history, person,
Portrait "), as shown in FIG. 7, based on the link control rule of the above equation (14), only the link of the link identifier m is visible at the node of the node identifier 10, whereas the node identifier 6 → To the reader who has followed the nodes in the order of 7 → 9 → 10 (the context is “history, clothes, portrait”), as shown in FIG. 8, the node with the node identifier 10 can see only the link with the link identifier n. To do so. That is, in the hypertext system 1, it is possible to provide information from the corresponding viewpoints to the readers who follow the network from the viewpoints of clothes and persons, respectively. That is, the author can dynamically introduce multiple contexts in this way.

(Specific Example 4) Next, node identifiers 14 to 2
An example of the network shown in FIG. 9 including nodes represented by 1 and links represented by link identifiers o to z will be described. This network shall be for information on technical papers on hypermedia.

A link control rule represented by the equations (16) to (27) is defined as an attribute for each link (link identifiers o, ..., Z) in this network.
Here, the link control rule of the link o is defined by the link control attribute of the node 14, the link control rule of the links p, r, and s is defined by the link control attribute of the node 15, and the link control rule of the link q is node 16. Defined by the link control attribute of the node x, the link control rule of the link x is defined by the link control attribute of the node 17, the link control rules of the links t, v, and w are defined by the link control attribute of the node 18, and the link of the link u. The control rule is defined by the link control attribute of the node 19, and the link control rules of the links y and z are defined by the link control attribute of the node 20.

[0057]

[Equation 4] Further, keywords of “hypertext”, “meaning of hypertext”, “hypermedia”, and “meaning of hypermedia” are defined for the nodes of the node identifiers 15, 16, 18, and 19, respectively. The node identifiers 16 and 19 describe the hypertext and hypermedia word / phrase definition information, the node identifiers 17 and 20 describe basic information, and the node identifier 21 describes the node. It is assumed that information on specialized matters is described.

This network will be described later.
It is designed to lead different routes between "beginner" and "expert", and is judged as "beginner" when the node (16 and / or 19) of the definition information of the hypertext and / or hypermedia word is traced. I am trying to do it.

If no keyword is set as the initial context for this network, the link control of the link identifier p, s of the links p, r, s connected to this node is performed at the node of the node identifier 15. A true logical result can be obtained only in the conditional expressions of the rules (17) and (20). As a result, the reader can select the link with the link identifier p or s.

Below, an example of the route of a reader who is not well understood is shown in FIG.
Will be described with reference to. For readers who have little understanding,
In the node of the node identifier 15, the link of the link identifier p can be selected, and subsequently, the text data and the like regarding the meaning of the hypertext can be provided.

When the node having the node identifier 16 is moved in this way, the context change expression of the expression (17) is executed in the processing procedure of step SP10, so that the keyword "beginner" is set to the keyword forming the context. Is added. As a result, in this case, the context is formed by the keywords “hypertext” and “beginner”, and when the reader subsequently returns to the node of the node identifier 15, the link identifiers p and r (17), (19), The true logical result is obtained only in the conditional expression.

As a result, in general, the reader selects the link of the unidentified link identifier r and
And moves to the node 20, and the hypertext control unit 6
Applies the context to the conditional expressions (26) and (27). In this case, since the keyword “hypermedia” has not been added to the context, the hypertext system 1 hides the link with the link identifier z, shows only the link with the link identifier y, and the reader follows this link. Move to the node with the node identifier 18.

At this time, the reader may deepen the understanding by understanding the meaning of the hypertext and by navigating the nodes having the node identifiers 17 and 20 sequentially. Therefore, the hypertext system 1
Executes the context change expression of Expression (26) to remove the keyword “beginner” from the context keywords, and then moves to the node of the node identifier 18.

The keyword "hypermedia" is added to the context for the reader who has visited the node of the node identifier 18. A reader who has a poor understanding even after following such a route moves to the node of the node identifier 19 as necessary to understand the "hypermedia meaning". For this reader, the context is formed by a keyword set of "hypertext", "hypertext meaning", "hypermedia", "hypermedia meaning", and "beginner". As a result, for such readers, the hypertext system 1 re-establishes the node identifier 1
It provides the information assigned to each node via nodes 7 and 20. Note that the node with the node identifier 20 is 2
By the time it reaches the first time, understanding may progress considerably,
The conditional expression of the link control rule (27) allows the node identifier 21 describing the technical matter to be transferred to the node.

On the other hand, it is possible to directly select the node having the node identifier 21 from the node having the node identifier 18 which has arrived first. In other words, it provides information about the meaning of hypertext, and also provides information on the basics of hypertext and hypermedia, which allows readers who have deepened their understanding rapidly to follow this rapid understanding. Directly from node with node identifier 18 to node identifier 2
It will allow the migration to one node and will provide information on specialized matters.

Next, an example of an expert route will be described with reference to FIG. As described above, when no keyword is set as the initial context, the node identifier 15
At the node, the reader may select the link with link identifier p or s. For the reader who has selected the link s connected to the node of the node identifier 18 at the node of the node identifier 15, the hypertext system 1 judges that it is an expert and directly navigates to the node of the node identifiers 18 and 21. Without providing unnecessary information to
Provides a semantically consistent set of information.

According to the above configuration, by assigning a keyword to each node, describing the context based on this keyword, and describing the appearance of the link with the control statement based on this keyword, Can provide readers with consistent information.

By forming a keyword set corresponding to the node selected by the reader and changing the context, further changing the context according to the control sentence corresponding to the link selected by the reader. , It is possible to form a semantically consistent context, and by updating this context and sequentially tracing the network, it is possible to provide a dynamic and large number of contexts easily and efficiently from the viewpoint of the author. it can.

Furthermore, since a dynamic link can be dynamically supplied according to the reader's understanding, necessary information can be provided according to the reader's understanding, and various kinds of information can be searched. .

Although the present invention is applied to the hypertext system in the above embodiment, it is needless to say that the present invention can be applied to other data retrieval devices, and the number and types of media are not limited. .

The data search device of the present invention may be constructed on a general-purpose device such as a personal computer or a workstation, or may be constructed as a dedicated search device.

[0072]

As described above, according to the present invention, a keyword is assigned to each node, a context is described based on this keyword, and a link appearance is described based on this keyword. By changing the context according to the link selected by the reader, even if the system becomes large-scale or complicated, it is possible to dynamically and massively form a semantically consistent context with a simple configuration.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of an embodiment.

FIG. 2 is a flowchart for explaining the operation of the hypertext control unit.

FIG. 3 is an explanatory diagram showing a first network for explaining navigation control.

FIG. 4 is an explanatory diagram of the first navigation.

FIG. 5 is an explanatory diagram of the second navigation.

FIG. 6 is an explanatory diagram showing a second network for explaining navigation control.

FIG. 7 is an explanatory diagram of navigation based on the keyword “person”.

FIG. 8 is an explanatory diagram of navigation based on the keyword “clothes”.

FIG. 9 is an explanatory diagram showing a third network for explaining navigation control.

FIG. 10 is an explanatory diagram when the beginner sails.

FIG. 11 is an explanatory diagram when the expert sails.

[Explanation of symbols]

1 ... Hypertext system, 2 ... Display unit, 3 ... Input unit, 4 ... Database unit, 5 ... User interface management unit, 6 ... Hypertext control unit, 8 ... Node information management unit, 9 ... Link information management unit, 7A , 7B ... Media data management unit.

Claims (7)

[Claims] 1. A data search for forming a network by a plurality of nodes defined corresponding to a plurality of data and a link connecting the plurality of nodes, and tracing the network to provide the data corresponding to the nodes. In the device, a data storage means for storing the data, a keyword storage means for storing a keyword of the data corresponding to the node, and the appearance of the link extending from each node are based on the keyword. A link description means for describing each link, a context description means for describing a context formed by tracing the network based on the set of the keywords, and a link description for visiting the node by tracing the network Search for means and extend from the visited node based on the context and the appearance of the link. A link that is allowed to be visited subsequently is detected from among the links, and a node that follows the detected link is visited, and the keyword storage means and the context description means are searched to visit subsequently. A navigation control means for updating the context in accordance with a link connected to a node and describing it in the context description means. 2. The navigation control means sets the union of the set of the keywords forming the context and the keywords assigned to the node to be subsequently visited in the contexts up to the following nodes. The data search device according to claim 1, wherein the context is updated according to a link connected to a node to be visited. 3. The link description means expresses the appearance of the link extending from each node by a control statement based on the keyword, and the navigation control means describes the formed set in the control statement. The data search device according to claim 1 or 2, wherein a link that is allowed to be subsequently visited is detected from the links that are fitted and extend from the visited node. 4. The control statement is formed by a context change logical expression that is formed based on the keyword and that changes the context, and the navigation control means is obtained by applying the context to the logical expression. Depending on the result, detect the link that is allowed to continue to extend from the node, execute the context change logic formula, and update the context according to the link leading to the subsequently visited node. The data search device according to claim 3, wherein 5. The navigation control means displays, via the display means, links that are allowed to be subsequently visited, and from the links that are allowed to be subsequently visited, a node that follows the link selected by the reader is displayed. The data search apparatus according to claim 1, wherein the data search apparatus visits. 6. The navigation control means further comprises keyword input means for inputting the keyword, wherein the navigation control means describes the keyword input via the keyword input means in the context description means and starts tracing the network. The initial context is set to
The data search device according to any one of 1. 7. The system further comprises history recording means for recording the visited nodes and the contexts that have been sequentially changed, and the navigation control means is recorded in the history recording means in response to an operation of a predetermined operator. According to the context, the context of the context description means is updated, and the node currently visited is backtracked to the node recorded in the history recording means, and the content of the history recording means is updated according to the backtracked node. The data search device according to claim 1, wherein