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EP0397992A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

"Unknown" response processing in a diagnostic expert system

Assignee: Bull HN Information Systems Inc
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Filing: 1990-03-21
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Granted: —
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Expires: 2010-03-21
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Abstract

Abstract A diagnostic expert system incorporating a cause-effect graph is disclosed in which "yes", "no" and "unknown" are valid possible responses to a query. Each node in the graph is assigned a local decision factor LDF) based on a given node's desirability for selection during best-first search and a collapsed decision factor (CDF) based on the average values of the LDFs for all its daughter nodes. For a current node being processed, a list of all its daughter nodes is obtained and examined to remove all daughter nodes that have been visited before in the current transition and all daughter nodes which have prerequisites that are not met. Then, the daughter node with the largest LDF is selected and its test function is executed. If the user response is "yes", the daughter node is made the current node, and a list of its daughter nodes is obtained to continue the process. If the user response is "no", the daughter node is added to the closed list, and the process continues with the next daughter node of the current node. If the user response is "unknown", the daughter node's CDF is compared with the LDFs for the other daughter nodes of the current node which are not on the closed list and which have their prerequisites met. If the CDF is larger than all the LDFs, the daughter node is made the current node to continue the process; otherwise, the daughter node with the largest LDF is selected, and its test function is executed to continue the process.

Inventors

  • 👤 Charles P. Ryan
  • 👤 Andrew Y. Pan
  • 👤 Thomas H. Howell
  • 👤 David W. Rolston

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-10-31 10:29
CPC Classifications
G; G06; G06F; G06F11/00; G06F11/22; G06F11/2257; G06N; G06N5/00; G06N5/04

Claims Analysis

Total Claims: 5
Claim 1
Independent Claim 320 words
In a diagnostic expert system incorporating a cause-­effect graph and in which "yes", "no" and "unknown" are valid possible responses to a query, the procedure for processing such responses which includes the following steps: A) assign to each node in the cause-effect graph a local decision factor based on a given node's desirability for selection during best-first search of the cause-effect graph; B) assign to each node in the cause-effect graph a collapsed decision factor based on the values of the local decision factors for all a given node's daughter nodes; and C) for a current node under examination: 1) obtain a list of all its daughter nodes; 2) examine a closed list to remove from the daughter node list all daughter nodes that have been visited before in the current transition; 3) remove from the daughter node list all daughter nodes which have prerequisites that are not met; 4) from the daughter nodes remaining, choose the daughter node with the largest local decision factor; and 5) execute the test function for the chosen daughter node: a) if the user response is "yes", make the chosen daughter node the current node and return to step C); b) if the user response is "no", add the chosen daughter node to the closed list and return to step C); and c) if the user response is "unknown", compare the chosen daughter node's collapsed decision factor with the local decision factors for the other daughter nodes of the current node which are not on the closed list and which have their prerequisites met and: i) if the collapsed decision factor is larger than all the local decision factors, make the chosen daughter node the current node and return to step C); and ii) if the collapsed decision factor is not larger than all the local decision factors, then chose the daughter node with the largest local decision factor and return to step 5).
Claim 2
Dependent Claim 320 words
In a diagnostic expert system incorporating a cause-­effect graph and in which "yes", "no" and "unknown" are valid possible responses to a query, the procedure for processing such responses which includes the following steps: A) assign to each node in the cause-effect graph a local decision factor based on a given node's desirability for selection during best-first search of the cause-effect graph; B) assign to each node in the cause-effect graph a collapsed decision factor based on the values of the local decision factors for all a given node's daughter nodes; and C) for a current node under examination: 1) obtain a list of all its daughter nodes; 2) examine a closed list to remove from the daughter node list all daughter nodes that have been visited before in the current transition; 3) remove from the daughter node list all daughter nodes which have prerequisites that are not met; 4) from the daughter nodes remaining, choose the daughter node with the largest local decision factor; and 5) execute the test function for the chosen daughter node: a) if the user response is "yes", make the chosen daughter node the current node and return to step C); b) if the user response is "no", add the chosen daughter node to the closed list and return to step C); and c) if the user response is "unknown", compare the chosen daughter node's collapsed decision factor with the local decision factors for the other daughter nodes of the current node which are not on the closed list and which have their prerequisites met and: i) if the collapsed decision factor is larger than all the local decision factors, make the chosen daughter node the current node and return to step C); and ii) if the collapsed decision factor is not larger than all the local decision factors, then chose the daughter node with the largest local decision factor and return to step 5).
Claim 3
Dependent Claim 31 words
The diagnostic expert system of Claim 1 in which, in step B), a given node's collapsed decision factor is determined by averaging the local decision factors for all its daughter nodes.
Claim 4
Dependent Claim 32 words
The diagnostic expert system of Claim 1 in which, in step B), if a given node is a terminal node, its collapsed decision factor is made equal to its local decision factor.
Claim 5
Dependent Claim 41 words
The diagnostic expert system of Claim 2 in which, in the event that a given node is a terminal node such that there are no daughter nodes to average, its collapsed decision factor is made equal to its local decision factor.

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