JPH0774995B2 - Qualitative reasoning system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a qualitative inference system capable of qualitatively analyzing causal relationships such as behaviors of devices and natural phenomena, and in particular, can reduce ambiguity of state transition occurring in behavior analysis. Ambiguity reduction method for simple qualitative reasoning system.

[0002]

2. Description of the Related Art A qualitative reasoning system captures a variable to be analyzed as a current value (or a range of values) and a state of change in the value. The state of change refers to increase, decrease, and constant 3
It is in a state. Then, the behavior of the device or the like is not analyzed in an analog manner, but only the points where the behavior changes are digitally analyzed. The points at which the behavior changes are, for example, when the ice is heated, when the temperature is 0 degrees and 100 degrees. In other words, the point where ice turns into water and water turns into steam,
This point is called a boundary mark (landmark). This digitally analyzed point is called an instantaneous state, and the interval between one instantaneous state and the next instantaneous state is called an interval state. This momentary condition occurs at one or more landmarks. Qualitative reasoning system, the instantaneous state and the state of the interval,
Also, the order of the state transitions is obtained.

Now, in the case of heating the ice, the variable having the landmark is only the temperature. Therefore, for example, if the temperature is given as an increasing state from −10 degrees as the initial state, (1) the temperature is −10.
(2) Temperature is from -10 degrees to 0
The state of the section when the temperature is 0 degree, (3) the instantaneous state when the landmark is 0 degree, (4) the state of the section when the temperature is 0 to 100 degrees, (5) the landmark is 100 degree It is required that the momentary state and the state transition at time. However, if there are multiple variables that have landmarks, it cannot be determined only from the value of which variable's landmark first transits. That is, ambiguity will occur.

In the conventional qualitative inference system, this ambiguity is resolved mainly by the generation-test method. This is a method of enumerating all possible solutions and obtaining only those combinations that satisfy the constraint. Possible solutions are, when moving from a section to a moment, when reaching a landmark or not, when moving from a moment to a section, when staying at a landmark and when moving. These are described in, for example, “Qualitative Reasoning; Knowledge Information Processing Series, Annex 1, Kyoritsu Shuppan”.

[0005]

The conventional generation-test method for resolving the ambiguity of state transitions requires enumerating all possible solutions at each transition from an interval to test the constraint of the combination. Therefore, there is a problem that the processing amount increases.

An object of the present invention is to eliminate the ambiguity of state transition without increasing the processing amount.

[0007]

[Means for Solving the Problem] The object to be analyzed
Structure information file that describes the structure of the
To register at least various relational expressions between
Various relational expressions between the knowledge base and the variables of the above objects
Of the working notes to register the relational expressions necessary for inference
And the objects registered in the working memory.
Based on the relational expression between
A constraint that solves a constraint problem to find the value of a variable or range of values.
About solver, above structure information file, above knowledge base
Use the above working memory and the above constraint solver
Qualitatively the behavior of the above objects based on physical quantities
Qualitative reasoning system with reasoning means for reasoning
The object described in the structure information file.
Structure and the above objects registered in the above knowledge base
According to the relational expression of
Approximately solver analyzes the above assumptions and
Of each object's variable so that there is no shielded state
A means for analyzing the momentary state for obtaining the value at the present moment, and the above-mentioned knowledge
Relational expression of the variables of the above objects registered in the knowledge base
In accordance with
Behavior changes from the current instant value of the variable
Land for estimating the variable landmarks for each object
Each of the marks obtained by the mark estimation means and the above-mentioned instantaneous state analysis means
The current instant value of the object variable and the
Each object whose behavior changes next estimated by the peak estimation means
The value of the landmark of the project variable is given as a constraint.
E, the above object described in the above structure information file
Structure and the above objects registered in the above knowledge base
Based on the above constraint conditions,
Constraint solver
Run variables for each object whose behavior changes from value to the next
The state of the section up to the mark is analyzed and each object's
In-state analysis means for obtaining the range of variable values, and
Relational expression of the variables of the above objects registered in the knowledge base
In accordance with the
Of each of the landmarks obtained by the above-mentioned section state analysis means.
Only include those that fall within the range of values of the object's variables.
The landmark determination unit that determines the final landmark
Achieving the above objectives by preparing for the above inference means
It

[0008]

Function: The range of the value of the next landmark estimated to be the value of the state at the current moment is given to each variable as a constraint condition. As a result, the constraint solver that solves the constraint problem of the expression, if the range of the given values is too wide and conflicts with other variables,
By limiting the range of the value, there is a feature that creates a state that is consistent with each other. In addition, the state at the moment of any of the landmarks obtained is next to the state at the current moment, and the constraint (value range) of the variable of the landmark is not limited even in the calculation of the constraint solver. Therefore, the landmark of the variable whose value range is limited does not become the landmark of the state at the next moment, and may be removed. In addition, since the constraint (value range) of the variable to be the next landmark or the variable whose relationship with other variables is not clearly described is not limited, the necessary landmark is not lost.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. In FIG. 1, knowledge of objects and physical laws is registered in a knowledge base 1. An example of a transistor object in an electronic circuit is shown in FIG. Here, it is described that the transistor has variables such as voltage, current, resistance, and current amplification factor (beta) for each terminal of the base, collector, and emitter. In addition, the transistor
It is defined to have two states, on and off, on condition of the base-emitter voltage (vbe @ Tr). That is, the voltage is on when the base-emitter voltage is 0.7 V or more, and is off when the voltage is less than 0.7 V. Then, a relational expression between variables that holds in each state is defined. For example, in the on state, the collector current (ir @ c!
For Tr), a relation (beta @ Tr * ir @ b! Tr) that is obtained by multiplying the base current by the current amplification factor is defined. That is, when the base-emitter voltage is 0.7 V or higher, the transistor is configured by a model of a relational expression between variables in the on state.

Next, the case where the present invention is applied to the analysis of the behavior of the Schmitt trigger circuit shown in FIG. 3 will be described as an example. An example of the description of the structure of the Schmitt trigger circuit is shown in FIG.
This is registered in the structure information file 2 of FIG. Here, the Schmitt trigger circuit has two transistors (T
r1, Tr2) and five resistors (RL1, etc.), and how each is connected is described (connect (...)). Further, the initial condition at the time of behavior analysis (the input voltage vr @ Inp = 10V in FIG. 4) is also registered here.

In the inference unit 3, first, the in-instantaneous-state analysis unit 31 is activated to perform initialization. That is, the initial conditions and the like are fetched from the structure information file 2 and registered in the working memory 4. Next, the structure described in the structure information file 2 is constructed. The structure information file 2 is shown in FIG.
As shown in, the circuit is said to consist of two transistors and five resistors, so knowledge base 1
The objects of 2 transistors and 5 resistors are copied and registered in the working memory 4. Specifically, the relational expression between the variables of the objects of FIG. 2 described in the knowledge base 1 is registered. Here, in the case of a transistor, the base-emitter voltage is often not determined until all elements of the circuit are registered. Therefore, when registering a transistor, it is not possible to decide whether to register the relational expression between variables in the on state or the relational expression between variables in the off state. In such a case,
The analysis is performed based on the assumption of four combinations when the base-emitter voltage of each of the transistors Tr1 and Tr2 is 0.7 V or more and when the voltage is less than 0.7 V.
Assuming that the base-emitter voltage of both the transistors Tr1 and Tr2 is 0.7 V or more, the relational expression between variables in the transistors Tr1 and Tr2 is registered in the working memory 4. The constraint solver 5 calculates the expression registered in the working memory 4 and calculates the value of the variable,
Or find the range of values. This constraint solver 5 can be realized by, for example, a linear programming method. In the case of the initial state of the Schmitt trigger circuit of FIG. 4, analysis can be performed without contradiction only when the transistor Tr1 is on and Tr2 is off. Other than that, there is an inconsistent state that cannot exist. Then, the base-emitter voltage of the transistor Tr1 is reduced to 0.705V, and the transistor Tr2
The base-emitter voltage of is at −4.613 V, which means that it is in an increasing state. The voltage of the resistor 1 is 5.5.
It can be found that the voltage is in a decreasing state at 37V.

Next, the landmark estimation unit 32 obtains the landmark of each variable based on the result of the instantaneous state analysis unit 31. The landmark is obtained from the conditions of the object. This is because the condition of the object indicates that the state of the object is changed, and the base-emitter voltage = 0.7V is a candidate for both the transistors Tr1 and Tr2. Here, the transistor Tr
The base-emitter voltage of 1 is 0.705V, and the base-emitter voltage of the transistor Tr2 decreases.
Since both are increased at −4.613 V, the base-emitter voltage = 0.7 V is obtained as a landmark in both cases.

After clearing the working memory 4, the intra-section state analysis unit 33 sets, as an initial condition, the value of the present moment state obtained by the intra-state state analysis unit 31 for each variable.
After the estimated value range of the next landmark is given as a constraint condition, the structure described in the structure information file 2 is constructed in the same manner as in the instantaneous state analysis unit 31. That is, the base-emitter voltage of the transistor Tr1 is 0.70.
5V to 0.7V, the base-emitter voltage of the transistor Tr2 is 0.7V to -4.613V, and the voltage of the resistor 1 is 5.537V, which is in a decreasing state, but a landmark is not detected. 537V or less is registered in the working memory 4 as an initial condition. When the structure is constructed based on the above, the base-emitter voltage of the transistor Tr1 is 0.705V to 0.703V, and the base-emitter voltage of the transistor Tr2 is 0.7V to −.
As it is 4.613V, the voltage of the resistor 1 is 5.537.
A range of values from V to 3.745V is calculated. The course of the above processing is shown in FIG.

The landmark determination unit 34 determines only the landmarks determined by the landmark estimation unit 32 as final landmarks within the range of the variable values determined by the intra-section state analysis unit 33. And Here, of the two landmarks of the base-emitter voltage of the transistors Tr1 and Tr2 obtained by the landmark estimation unit 32 = 0.7 V, the base of the transistor Tr1−
As a result of the intra-section state analysis unit 33, the value of the emitter-to-emitter voltage is 0.705V to 0.703V, and the landmark of the transistor Tr1 (base-emitter voltage =
0.7V) is not included in this, and thus is removed from the landmark. Therefore, in the next process of the instantaneous in-state analysis unit 31, it is only necessary to solve the case where the base-emitter voltage of the transistor Tr2 is 0.7V and the base-emitter voltage of the transistor Tr1 is> 0.7V. Therefore, the ambiguity of the state transition can be reduced to 1/3.

[0015]

According to the present invention, it is possible to reduce the ambiguity of the next instantaneous state from the state analysis of an interval.
The amount of inference processing can be reduced and high-speed inference can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a diagram showing a knowledge representation of an object of the present invention by taking a transistor as an example.

FIG. 3 is a circuit diagram of a Schmitt trigger circuit.

FIG. 4 is a diagram showing a description example of a circuit structure when the present invention is applied to behavior analysis of a Schmitt trigger circuit.

FIG. 5 is a diagram showing a transition of calculation results of each variable when the present invention is applied to behavior analysis of a Schmitt trigger circuit.

[Explanation of symbols]

1 ... Knowledge base, 2 ... Structural information file, 3 ... Inference section,
4 ... Working memory, 5 ... Constraint solver, 31 ... In-state analysis unit, 32 ... Landmark estimation unit, 33 ... Section analysis unit, 34 ... Landmark determination unit.

 ─────────────────────────────────────────────────── ─── Continued Front Page (56) References ICOT TECHNICAL REP ORT TR-738 (1992-2)

Claims (1)

[Claims] 1. A structure of an object to be analyzed is described.
Structure information file and various relational expressions between the variables of the above objects.
Inference among the relational expressions between the knowledge base to be registered and the variables of the above objects
A working memory for registering a relation required, the object registered in the working memory
Based on the relational expression between variables,
Constraint Sol Solving Constraint Problem to Find Value or Range of Values
Bar, above structure information file, above knowledge base, above workin
Based on the physical quantity using the memory and the constraint solver above.
Based on the reasoning method to qualitatively infer the behavior of the above objects
In a qualitative inference system with a stage, the object of the above described in the above structure information file
Structure and of the above objects registered in the above knowledge base
According to the relational expression of variables, the above constraint
Analyze the above assumptions with the louver and contradict each object
Variable of each object so that there is no state
Of the instantaneous state analysis means for obtaining the instantaneous value of
According to the relational expression, each o
Behavior changes from the current instant value of the object's variable.
The landmarks for the variables of each object to be visualized
Variables of each object obtained by the landmark estimation means and the above-mentioned instantaneous state analysis means
The value at the current moment of
Run of variables for each object whose behavior changes next
Given the value of the mark as a constraint,
Structure of the object described in the file and the knowledge base
According to the relational expressions of the variables of the above objects registered in the
Based on the above constraint conditions, each constraint solver
Behavior changes from the current instant value of the object's variable
Of the interval to the landmark of the variable of each object
Analyze the state and find the range of values of variables of each object
That the in analyzing unit interval condition, registered in the knowledge base variable of the object
It is estimated by the landmark estimation means according to the relational expression.
Of the landmarks that have been
Although it is included in the range of the value of the variable of each object
Landmark decision which decides only as final landmark
Reasoning, characterized in that the inference means is provided with
system.