Truth value calculator with built-in resolution algorithm.
These are the following operators that are supported:
| Type | Symbol |
|---|---|
| Conjunction | & |
| Disjunction | + |
| Negation | ~ |
| Exclusive-Or | # |
| Implication | > |
| Biconditional | = |
When creating an expression, the library only accepts a specific format.
- All propositions, whether single or not, must be contained in parentheses. Ex: (A & B) + (C)
- External negations are not yet available. Please convert with De Morgan's. Ex: ~(A + B) -> (~A & ~B)
Take the expresssion (P + R) & (Q + ~R) & (~Q) & (~P + G) & (S + ~G) & (~S) for example,
and compute the truth value for the following boolean map:
P -> FALSE
Q -> FALSE
G -> FALSE
R -> TRUE
S -> TRUE
... then compute the resolution method.
/* expression */
String expression = "(P + R) & (Q + ~R) & (~Q) & (~P + G) & (S + ~G) & (~S)";
/* set the proposition values */
Map<Character, Boolean> truthValues = new HashMap<>();
truthValues.put('P', false);
truthValues.put('Q', false);
truthValues.put('G', false);
truthValues.put('R', true);
truthValues.put('S', true);
/* create a new logical formula from the expression */
LogicalFormula formula = new LogicalFormula(expression);
/* calculate the truth value */
formula.calculate(truthValues);
System.out.println(formula.getExpression() + " is " + formula.getTruthValue());
System.out.println();
/* execute the resolution method */
new LogicalResolution(formula).execute();(P + R) & (Q + ~R) & (~Q) & (~P + G) & (S + ~G) & (~S) is false
{{~S}, {~Q}, {P, R}, {Q, ~R}, {~P, G}, {S, ~G}}
[0] Replacing {Q, ~R} and {~Q} with {~R}
{{~S}, {P, R}, {~P, G}, {S, ~G}, {~R}}
[1] Replacing {P, R} and {~R} with {P}
{{~S}, {~P, G}, {S, ~G}, {P}}
[2] Replacing {~P, G} and {P} with {G}
{{~S}, {S, ~G}, {G}}
[3] Replacing {S, ~G} and {~S} with {~G}
{{G}, {~G}}
[4] Replacing {~G} and {G} with ?
{?}
Empty clause found!- Resolution method does not break when an empty clause is not found.
- Note: This library is still under development. Please report any issues here.
MIT License
Copyright (c) 2020 Christian Horton
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.