Patent Application
20220414479
The present invention relates to a contradiction detection apparatus and a contradiction detection method for detecting contradictions in a derivation of hypotheses by applying inferential knowledge to observed events, and further relates to a computer-readable recording medium that includes recorded thereon, a program for realizing the apparatus and the method.
Conventionally, a method called abduction has been known as a type of logical inference. Abduction is a method of deriving the best hypothesis from given knowledge (rules) and observed events (obtained facts). For example, it is assumed that “A=>B (if A is true, then B is true)” exists as knowledge, and “B is true” is acquired as an observed event. In this case, “A is true” is obtained as a hypothesis by inference.
The above abduction has been attempted to be performed by computers (see, for example, Patent Document 1). Abduction by computers makes it possible to infer various situations based on information obtained from facts. Abduction by computers is therefore useful for planning store openings, criminal investigations, disaster evacuation, environmental management, or the like, and the use of abduction can be expected to improve the accuracy of simulations.
However, in the abduction, if the observed event is inconsistent with the knowledge, the correct hypothesis cannot be derived. In such cases, there is a risk of wasting time by performing useless inferences, and also of not being able to derive correct inference results. Therefore, it is desirable to find a contradiction of the observed event.
An example of object of the present invention is to provide a contradiction detection apparatus, a contradiction detection method and a computer-readable recording medium that can find a contradiction of an observed event.
In order to achieve the above object, a contradiction detection apparatus in one aspect of the present invention detects whether an observed event is inconsistent with a knowledge base,
the contradiction detection apparatus includes:
a construction means for constructing a decision graph that has observed events as nodes and a transition relationship of each observed event as an edge, and outputs a boolean value of an observed event based on the knowledge base,
a reception means for receiving an observed event,
an elimination means for eliminating an edge, which transitions to a side denying the observed event received by the reception means, among edges connected to a node corresponding to the observed event received by the reception means in the decision graph,
a determination means for determining whether both paths from a root node to a true leaf node and a false leaf node exist in the decision graph after the edge is eliminated by the elimination means,
a repetition means for causing the reception means, the elimination means, and the determination means to repeatedly execute processing when the determination means determines that the paths exist, and
a decision means for deciding that the observed event is inconsistent with the knowledge base when the determination means determines that the paths does not exist.
Further, in order to achieve the above object, a contradiction detection method in one aspect of the present invention detects whether an observed event is inconsistent with a knowledge base,
the contradiction detection method includes:
constructing a decision graph that has observed events as nodes and a transition relationship of each observed event as an edge, and outputs a boolean value of an observed event based on the knowledge base,
receiving an observed event,
eliminating an edge, which transitions to a side denying the observed event received, among edges connected to a node corresponding to the observed event received in the decision graph,
determining whether both paths from a root node to a true leaf node and a false leaf node exist in the decision graph after the edge is eliminated,
repeatedly executing a reception of the observed event, an elimination of the edge, and a determination of existence of the paths when it is determined that the paths exist, and
deciding that the observed event is inconsistent with the knowledge base when it is determined that the paths does not exist.
Further, in order to achieve the above object, a computer-readable recording medium according to an example aspect of the invention includes a program recorded thereon, the program including instructions that cause a computer, which detects whether an observed event is inconsistent with a knowledge base, to execute:
constructing a decision graph that has observed events as nodes and a transition relationship of each observed event as an edge, and outputs a boolean value of an observed event based on the knowledge base,
receiving an observed event,
eliminating an edge, which transitions to a side denying the observed event received, among edges connected to a node corresponding to the observed event received in the decision graph,
determining whether both paths from a root node to a true leaf node and a false leaf node exist in the decision graph after the edge is eliminated,
repeatedly executing a reception of the observed event, an elimination of the edge, and a determination of existence of the paths when it is determined that the paths exist, and
deciding that the observed event is inconsistent with the knowledge base when it is determined that the paths does not exist.
According to the present invention, it is possible to find the contradiction of the observed event with respect to the knowledge base.
Hereinafter, a contradiction detection apparatus, a contradiction detection method, and a computer-readable recording medium according to the example embodiment of the present invention will be described with reference to the drawings.
First, a schematic configuration of the contradiction detection apparatus according to the example embodiment 1 will be described with reference to
The contradiction detection apparatus 1 is an apparatus that detects whether an observed event is inconsistent with a knowledge base. The contradiction detection apparatus 1 includes a construction unit 11, a reception unit 12, an elimination unit 13, a determination unit 14, a repetition unit 15, and a decision unit 16.
The construction unit 11 constructs a decision graph, which has observed events as nodes and a transition relationship of each observed event as an edge and outputs a boolean value of the observed event based on the knowledge base.
The reception unit 12 receives the observed event.
The elimination unit 13 eliminates the edge, which transitions to a side denying the observed event, among the edges connected to the node corresponding to the observed event received by the reception unit 12 in the decision graph.
The determination unit 14 determines whether both paths from a root node to a true leaf node and a false leaf node exist in the decision graph after the edge is eliminated by the elimination unit 13.
The repetition unit 15 causes the reception unit 21, the elimination unit 13, and the determination unit 14 to repeatedly execute processing when the determination unit 14 determines that the paths exist.
The decision unit 16 decides that the observed event is inconsistent with the knowledge base when the determination unit 14 determines that the paths does not exist.
According to the contradiction detection apparatus 1 of the above example embodiment 1, it is possible to detect that the observed event is inconsistent with the knowledge base.
Subsequently, the configuration and functions of the contradiction detection apparatus 1 according to the example embodiment 1 will be specifically described.
The contradiction detection apparatus 1 includes the minimal unsatisfiable set detection apparatus 30 in addition to the construction unit 11, the reception unit 12, the elimination unit 13, the determination unit 14, the repetition unit 15, and the decision unit 16 described above.
The construction unit 11 constructs the decision graph based on a knowledge base 50. The knowledge base 50 is data for performing the abduction. The knowledge base 50 is stored in a storage device not shown in the figure. The storage device may be provided outside the contradiction detection apparatus 1 or may be provided in the contradiction detection apparatus 1.
The knowledge base 50 is expressed, for example, by an implication relation rule of a first-order predicate logic formula. The knowledge base 50 is expressed in the form of, for example, “pre-state (premise)=>post-state (conclusion)”. This form indicates that if the pre-state, which is the premise to be observed, is true, then the post-state, which is the inevitable conclusion, is derived. In this form, the “post-state” is a necessary condition for the “pre-state” to be true. The “pre-state” is a sufficient condition for the “post-state” to be true. The sufficient condition can also be expressed as a conjunction of multiple propositions. For example, the knowledge base 50 may be expressed as “pre-state (premise) A action=>post-state”.
With reference to
The reception unit 12 receives the observed event 51. The elimination unit 13 eliminates the edge, which transitions to a side denying the observed event 51, among the edges connected to the node corresponding to the observed event 51 received by the reception unit 12. The edge that transitions to the side denying the observed event 51 is, for example, when the observed event 51 is “U”, the edge of “False” (the edge (A) in
The determination unit 14 determines reachability in the decision graph after the edge is eliminated by the elimination unit 13. Reachability is the presence or absence of a first path from the root node to the leaf node “True” and a second path from the root node to the leaf node “False”. The determination unit 14 determines that there is reachability when the first path and the second path exist, and determines that there is no reachability when the first path or the second path does not exist. In the decision graph shown in
When the determination unit 14 determines that there is reachability, the repetition unit 15 causes the reception unit 12, the elimination unit 13, and the determination unit 14 to execute the processing again. Specifically, the reception unit 12 receives “¬S”, which is the next observed event 51. The elimination unit 13 eliminates the edge of “True” connected to the node “S” (the edge (B) in
Return to
The minimal unsatisfiable set detection apparatus 30 is an apparatus that detects a minimal set covering from multiple observed events 51 that are inconsistent with the knowledge base 50. The minimal unsatisfiable set detection apparatus 30 may be independent of the contradiction detection apparatus 1. As shown in
The decision graph acquisition unit 31 acquires the decision graph constructed by the construction unit 11.
The observed event acquisition unit 32 acquires a plurality of observed events 51 decided to be inconsistent with the knowledge base by the decision unit 16. In the example embodiment 1, the plurality of observed events 51 decided to be inconsistent are “U”, “¬S”, “W”, “¬T”, and “P”.
The minimal set covering derivation unit 33 converts the plurality of observed events 51 acquired by the observed event acquisition unit 32 into a minimal set covering problem using a decision graph, and obtains a minimal set covering. The minimal set covering derivation unit 33 includes an extraction unit 331, an assignment unit 332, a detection unit 333, and an association unit 334.
The extraction unit 331 extracts all of the first paths from the root node to the leaf node “True” or the second paths from the root node to the leaf node “False” in the decision graph. The extraction unit 331 extracts all of the first or second paths for which it is determined that reachability does not exist. In the example embodiment 1, the determination unit 14 determines that there is no reachability of the first path. In this case, the extraction unit 331 extracts all of the first paths.
The assignment unit 332 assigns path numbers to all the first paths extracted by the extraction unit 331.
The detection unit 333 detects which of the plurality of observed events 51 acquired by the observed event acquisition unit 32 is observed to block the first paths to which path numbers (1) to (4) are assigned. For example, when the observed event 51 is “¬S”, the first paths with path numbers (2) and (3) are blocked.
The association unit 334 associates the observed event 51 detected by the detection unit 333 with the path number of the first path blocked by the observed event 51.
The minimal set covering derivation unit 33 obtains the minimal set covering of all path numbers from the observed events 51 to which the path numbers are associated. That is, the minimal set covering derivation unit 33 finds the smallest combination of observed events 51 that satisfies all the path numbers (1) to (4). In the case of
The output unit 34 outputs the result of the minimal set covering obtained by the minimal set covering derivation unit 33. Note that, when the decision unit 16 detects a contradiction, the output unit 34 may output “U”, “¬S”, “W”, “¬T”, and “P” as the observed events 51 received by the reception unit 12 before the contradiction is decided. Further, the output unit 34 may output to the outside of the contradiction detection apparatus 1, or may output to a display device when the contradiction detection apparatus 1 includes the display device, for example.
Next, the operation of the contradiction detection apparatus 1 according to the example embodiment 1 will be described with reference to
The construction unit 11 acquires the knowledge base 50 and constructs a decision graph (S1). Next, the reception unit 12 determines whether the observation of the event is completed (S2), and if not (S2: NO), receives one observed event 51 (S3). When the observation of the event is completed (S2: YES), this process is completed.
In the decision graph constructed in S1, the elimination unit 13 eliminates the edge, which transitions to the side denying the observed event 51, among the edges connected to the node corresponding to the observed event 51 received in S3, as described in
When there is reachability (S6: YES), the repetition unit 15 causes the reception unit 12, the elimination unit 13, and the determination unit 14 to repeatedly execute each of the processes S2 to S5. When there is no reachability (S6: NO), the decision unit 16 decides that the observed events 51 received so far is inconsistent with the knowledge base 50 (S7). Then, the minimal unsatisfiable set detection apparatus 30 executes the minimal set covering calculation process (S8).
The decision graph acquisition unit 31 acquires the decision graph constructed by the construction unit 11 (S11). The observed event acquisition unit 32 acquires the plurality of observed events 51 decided to be inconsistent by the decision unit 16 (S12). In the decision graph acquired in S11, the extraction unit 331 of the minimal set covering derivation unit 33 extracts all of the first paths from the root node to the leaf node “True” or the second paths from the root node to the leaf node “False” (S13).
As shown in
The minimal set covering derivation unit 33 calculates the minimal set covering of all path numbers from the observed events 51 to which the path numbers are associated in S16 (S17). Then, the output unit 34 outputs the calculated minimal set covering (S18).
Note that, if the contradiction detection apparatus 1 does not include the minimal unsatisfiable set detection apparatus 30, the above processes S11 to S17 may be omitted. In this case, the contradiction detection apparatus 1 may include an output unit, and after determining in S7 of
It is sufficient for the program according to the example embodiment 1 of the present invention to be a program that causes a computer to execute steps S1 to S8 shown in
Also, the program according to the example embodiment 1 may be executed by a computer system constituted by a plurality of computers. In this case, for example, each computer may function as any of the construction unit 11, the reception unit 12, the elimination unit 13, the determination unit 14, the repetition unit 15, and the decision unit 16.
According to the contradiction detection apparatus 1 according to the example embodiment 1, it is possible to find the contradiction of the observed event 51 with respect to the knowledge base 50.
Next, a contradiction detection apparatus, a contradiction detection method, and a computer-readable recording medium according to the example embodiment 2 of the present invention will be described with reference to the drawings. In the example embodiment 2, the method of determining the reachability with respect to the knowledge base is different from the example embodiment 1. The differences will be described below. Note that in the following, the same configuration as that of the example embodiment 1 will be described with the same reference numerals. Further, the contradiction detection apparatus of the example embodiment 2 does not include the minimal unsatisfiable set detection apparatus 30.
The contradiction detection apparatus 2 includes the construction unit 11, the reception unit 12, the elimination unit 13, the determination unit 14, the repetition unit 15, the decision unit 16, a grounding operation unit 17, and an output unit 18.
The grounding operation unit 17 performs a grounding operation based on the Herbrand universe of the knowledge base 50. As described in the example embodiment 1, the knowledge base 50 is expressed by the implication relation rule of the first-order predicate logic formula. The Herbrand universe is a region where constants that can be assigned in the variables of each predicate are fixed for the first-order predicate logic formula. The grounding operation is a process of substituting the constants of the Herbrand universe into the first-order predicate logic formula so that it can be treated as a propositional logic formula.
For example, if there is a predicate called Eat (people, food), “people” and “food” are variables of the predicate. The Herbrand universe is “people={Andy, Bob, Cathy}”, “food={Donuts, Eggs, Fish}” and so on. In this case, the grounding operation generates Eat (Andy, Donut), Eat (Andy, Egg), Eat (Cath, Fish) and the like as propositional logic formula.
The construction unit 11 constructs a decision graph from the propositional logic formula generated by the grounding operation unit 17. In the example embodiment 2, the construction unit 11 constructs the decision graph shown in
The reception unit 12 and the elimination unit 13 are the same as those in the example embodiment 1.
The determination unit 14 includes a link operation unit 141 and a label operation unit 142.
For a node having only one internal node as a child node in the decision graph in which the edge is eliminated by the elimination unit 13, the link operation unit 141 puts a link to the one internal node. The internal node is a node that has child node. For example, when the observed event 51 is “U”, the elimination unit 13 eliminates the edge of “False” connected to the node “U”. In this case, the “one internal node” is the node “S”, and the “node having only one internal node” is the node “U”. The link operation unit 141 puts the link L1 to the node “S” on the node “U”.
For a node having only one leaf node as a final transition destination, the label operation unit 142 attaches a label of “True” or “False” corresponding to the one leaf node. For example, when the observed event 51 is “¬S”, the elimination unit 13 eliminates the edge of “True” connected to the node “S”. As a result, the node “S” transitions only to the leaf node “False”. The label operation unit 142 attaches a “False” label (represented by (F) in
Further, when the final transition destination of a parent node of the labeled node is only the same leaf node as the final transition destination of the labeled node, the label operation unit 142 also attaches the same label to the parent node. In the above example, a parent node of the node “S” is the node “U”. The transition destination of the node “U” is only the node “S”, and the node “S” transitions only to the leaf node “False”. Therefore, the final transition destination of the node “U” is the leaf node “False”. In this case, the label operation unit 142 also attaches a “False” label to the node “U”.
When the root node (node “P”) is labeled by the label operation unit 142, the determination unit 14 determines that both paths from the root node to the “True” and “False” leaf nodes do not exit. That is, in this case, the determination unit 14 determines that there is no reachability. On the other hand, when the root node is not labeled, the determination unit 14 determines that both paths from the root node to the “True” and “False” leaf nodes exist. That is, in this case, the determination unit 14 determines that there is reachability.
The repetition unit 15 causes the reception unit 12, the elimination unit 13, and the determination unit 14 to execute the processing again when the determination unit 14 determines that there is reachability.
Next, the operation of the contradiction detection apparatus 2 according to the example embodiment 2 will be described with reference to
First, the grounding operation unit 17 generates the propositional logic formula by performing the grounding operation based on the Herbrand universe of the knowledge base 50 (S21). The construction unit 11 constructs the decision graph from the propositional logic formula generated in S21 (S22). Next, the reception unit 12 determines whether the observation of the event is completed (S23), and if not (S23: NO), receives one observed event 51 (S24). When the observation of the event is completed (S23: YES), this process is completed.
In the decision graph constructed in S21, the elimination unit 13 eliminates the edge, which transitions to the side denying the observed event 51, among the edges connected to the node corresponding to the observed event 51 received in S23 (S25). Then, the determination unit 14 performs determination process to determine the reachability in the decision graph after the edge is eliminated (S26). The determination process is a process of attaching the link or the label to the node, which will be described in detail later.
When there is reachability (S27: YES), the repetition unit 15 causes the reception unit 12, the elimination unit 13, and the determination unit 14 to repeatedly execute each of the processes S23 to S26. When there is no reachability (S27: NO), the decision unit 16 decides that the received observed events 51 is inconsistent with the knowledge base 50 (S28). Then, the output unit 18 outputs the observed event 51 received by the reception unit 12 before the contradiction is decided (S29).
(Case where Observed Event 51 is “U”)
When the observed event 51 is “U”, the edge of “False” connected to the node “U” is eliminated in S25 of
The label operation unit 142 determines whether the final transition destination of the node “U” is the one leaf node (S33). As shown in
(Case where Observed Event 51 is “¬S”)
When the observed event 51 is “¬S”, the edge of “True” connected to the node “S” is eliminated in S25 of
The label operation unit 142 determines whether the final transition destination of the node “S” is the one leaf node (S33). As shown in
The label operation unit 142 determines whether the final transition destination of the parent node “U” of the node “S” is the one leaf node (S35). As shown in
Subsequently, the label operation unit 142 determines whether the final transition destination of the parent node “R” of the node “U” is the one leaf node (S35). As shown in
The label operation unit 142 determines whether the final transition destination of the parent nodes “Q” and “T” of the node “R” is the one leaf node (S35). As shown in
(Case where Observed Event 51 is “¬T”)
The link operation unit 141 determines whether the child node of the node “T” is only one internal node (S31). As shown in
The label operation unit 142 determines whether the final transition destination of the node “T” is the one leaf node (S33). As shown in
Subsequently, the label operation unit 142 determines whether the final transition destination of the parent node “Q” of the node “T” is the one leaf node (S35). As shown in FIG. 18, the transition destination of the node “Q” is the nodes “T” and “R” labeled with “False”. That is, the final transition destination of the node “Q” is the leaf node “False”. In this case (S35: YES), the node “Q” is labeled with “False” (S34).
The label operation unit 142 determines whether the final transition destination of the parent node “P” of the node “Q” is the one leaf node (S35). As shown in
(Case where Observed Event 51 is “P”)
The link operation unit 141 determines whether the child node of the node “P” is only one internal node (S31). As shown in
The label operation unit 142 determines whether the final transition destination of the node “P” is the one leaf node (S33). As shown in
The node “P” is a root node and has no parent node. In this case (S35: NO), the determination unit 14 determines whether the label is attached to the root node (S36). As shown in
It is sufficient for the program according to the example embodiment 2 of the present invention to be a program that causes a computer to execute steps S21 to S29 shown in
Also, the program according to the example embodiment 2 may be executed by a computer system constituted by a plurality of computers. In this case, for example, each computer may function as any of the construction unit 11, the reception unit 12, the elimination unit 13, the determination unit 14, the repetition unit 15, the decision unit 16, the grounding operation unit 17, and the output unit 18.
According to the contradiction detection apparatus 1 according to the example embodiment 2, it is possible to find the contradiction of the observed event 51 with respect to the knowledge base 50. Further, in comparison with the example embodiment 1, by attaching the label of the final transition destination to each node, the reachability determination process can be speeded up. As a result, the processing time for detecting a contradiction can be shortened.
Here, a computer that realizes the contradiction detection apparatus by executing the programs in the example embodiments 1 and 2 will be described with reference to
As illustrated in
The CPU 111 loads the programs (codes) in the example embodiments 1 and 2, which are stored in the storage device 113, onto the main memory 112, and performs various computations by executing these codes in a predetermined order. The main memory 112 is typically a volatile storage device such as a dynamic random access memory (DRAM). Furthermore, the programs in the example embodiments 1 and 2 are provided in a state such that the program is stored in a computer readable recording medium 120. Note that the programs in the example embodiments 1 and 2 may also be programs that are distributed on the Internet, to which the computer 110 is connected via the communication interface 117.
In addition, specific examples of the storage device 113 include semiconductor storage devices such as a flash memory, in addition to hard disk drives. The input interface 114 mediates data transmission between the CPU 111 and input equipment 118 such as a keyboard and a mouse. The display controller 115 is connected to a display device 119, and controls the display performed by the display device 119.
The data reader/writer 116 mediates data transmission between the CPU 111 and the recording medium 120, and executes the reading out of the program from the recording medium 120 and the writing of results of processing in the computer 110 to the recording medium 120. The communication interface 117 mediates data transmission between the CPU 111 and other computers.
Furthermore, specific examples of the recording medium 120 include a general-purpose semiconductor storage device such as a CompactFlash (registered trademark, CF) card or a Secure Digital (SD) card, a magnetic recording medium such as a flexible disk, and an optical recording medium such as a compact disk read-only memory (CD-ROM).
Note that the contradiction detection apparatuses in the example embodiments 1 and 2 can also be realized by using pieces of hardware corresponding to the respective units, rather than using a computer on which the program is installed. Furthermore, a portion of the contradiction detection apparatus may be realized by using a program, and the remaining portion of the contradiction detection apparatus may be realized by using hardware.
While a part of or the entirety of the above-described example embodiment can be expressed by (Supplementary note 1) to (Supplementary note 15) described in the following, the invention is not limited to the following description.
A contradiction detection apparatus that detects whether an observed event is inconsistent with a knowledge base, the contradiction detection apparatus comprising:
a construction means for constructing a decision graph that has observed events as nodes and a transition relationship of each observed event as an edge, and outputs a boolean value of an observed event based on the knowledge base,
a reception means for receiving an observed event,
an elimination means for eliminating an edge, which transitions to a side denying the observed event received by the reception means, among edges connected to a node corresponding to the observed event received by the reception means in the decision graph,
a determination means for determining whether both paths from a root node to a true leaf node and a false leaf node exist in the decision graph after the edge is eliminated by the elimination means,
a repetition means for causing the reception means, the elimination means, and the determination means to repeatedly execute processing when the determination means determines that the paths exist, and
a decision means for deciding that the observed event is inconsistent with the knowledge base when the determination means determines that the paths does not exist.
The contradiction detection apparatus according to Supplementary note 1, further comprising:
an output means for outputting an observed event received by the reception means before a contradiction is decided when the determination means determines a contradiction.
The contradiction detection apparatus according to Supplementary note 1 or 2, wherein
the determination means comprises:
the determination means determines that both paths from a root node to a true leaf node and a false leaf node do not exist when the label operation means attaches the label to the root node.
The contradiction detection apparatus according to Supplementary note 3, wherein
when a final transition destination of a parent node of the node to which a label is attached by the label operation means, is only one leaf node, the label operation means attaches the label to the parent node.
The contradiction detection apparatus according to any one of Supplementary notes 1 to 4, further comprising:
a grounding operation means for performing grounding operation based on Herbrand universe of the knowledge base, wherein
the construction means constructs the decision graph based on an operation result by the grounding operation means.
A contradiction detection method that detects whether an observed event is inconsistent with a knowledge base, the method comprising:
constructing a decision graph that has observed events as nodes and a transition relationship of each observed event as an edge, and outputs a boolean value of an observed event based on the knowledge base,
receiving an observed event,
eliminating an edge, which transitions to a side denying the observed event received,
among edges connected to a node corresponding to the observed event received in the decision graph,
determining whether both paths from a root node to a true leaf node and a false leaf node exist in the decision graph after the edge is eliminated,
repeatedly executing a reception of the observed event, an elimination of the edge, and a determination of existence of the paths when it is determined that the paths exist, and
deciding that the observed event is inconsistent with the knowledge base when it is determined that the paths does not exist.
The contradiction detection method according to Supplementary note 6, wherein
when the observed event is decided to be inconsistent, outputting an observed event received before a contradiction is decided.
The contradiction detection method according to Supplementary note 6 or 7, wherein
when determining whether the paths exist:
The contradiction detection method according to Supplementary note 8, wherein
when a final transition destination of a parent node of the node to which the label is attached is only one leaf node, attaching the label to the parent node.
The contradiction detection method according to any one of Supplementary notes 6 to 9, further comprising:
performing grounding operation based on Herbrand universe of the knowledge base, wherein
when constructing the decision graph, the decision graph is constructed based on an operation result of the grounding operation.
A computer-readable recording medium that includes recorded thereon, a program including instructions that cause a computer, which detects whether an observed event is inconsistent with a knowledge base, to execute:
constructing a decision graph that has observed events as nodes and a transition relationship of each observed event as an edge, and outputs a boolean value of an observed event based on the knowledge base,
receiving an observed event,
eliminating an edge, which transitions to a side denying the observed event received, among edges connected to a node corresponding to the observed event received in the decision graph,
determining whether both paths from a root node to a true leaf node and a false leaf node exist in the decision graph after the edge is eliminated,
repeatedly executing a reception of the observed event, an elimination of the edge, and a determination of existence of the paths when it is determined that the paths exist, and
deciding that the observed event is inconsistent with the knowledge base when it is determined that the paths does not exist.
The computer-readable recording medium according to Supplementary note 11, wherein
when the observed event is decided to be inconsistent, outputting an observed event received before a contradiction is decided.
The computer-readable recording medium according to Supplementary note 11 or 12, wherein
when determining whether the paths exist:
The computer-readable recording medium according to Supplementary note 13, wherein
when a final transition destination of a parent node of the node to which the label is attached is only one leaf node, attaching the label to the parent node.
The computer-readable recording medium according to any one of Supplementary notes 11 to 14, the program further including instructions that cause a computer to execute:
performing grounding operation based on Herbrand universe of the knowledge base, wherein
when constructing the decision graph, the decision graph is constructed based on an operation result of the grounding operation.
As described above, the present invention is useful in in the field of deriving hypotheses by applying inferential knowledge to observed events.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2019/025592 | 6/27/2019 | WO |
