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Logic

Logic library provides a convenient way of representing a logic expression. It also allows you to perform basic operations with a logic expression(generate a truth table, find the solution with a given tuple of values). Additionally, the library features include a generation of a random logic expression, equivalent and not equivalent to a particular expression.

##Usage ####LogicExpression class First of all, you should instantiate a LogicExpression class by passing string representation into its constructor:

LogicExpression expression = new LogicExpression("p" + LogicSymbols.AND + "q" + LogicSymbols.EQU + "r");

Note that you can use either a set of LogicSymbols constants or raw unicode symbols, while creating an object:

LogicExpression expression2 = new LogicExpression("p∧q→r");

There are four operations supported by this library:

  • conjunction (LogicSymbols.AND or \u2227 unicode symbol);
  • disjunction (LogicSymbols.OR or \u2227 unicode symbol);
  • implication (LogicSymbols.IMP or \u2227 unicode symbol);
  • equivalence (LogicSymbols.EQU or \u2227 unicode symbol).

Before performing some operation, a reversed polish notation should be created, you can do it by calling makeRPolishRecord method:

expression.makeRPolishRecord();

This method creates a notation and stores it in a California property. After that, this property is used in other methods of the class. Let's see all the rest of the methods:

  • EOperand calculate() method performs a computation with existing values stored in a operands property;
  • EOperand calculate(params bool[] x) method performs a computation with given tuple of boolean values;
  • TruthTable generateTruthTable() method generates a truth table.

LEGenerator class

First of all, you should create an object-generator:

LEGenerator g = new LEGenerator();

LEGenerator class has an interface that's similar to a Random class. There are few methods in the class:

  • LogicExpression next() generates a random logic expression;
  • LogicExpression next(int maxVarsNumber) does as same as the next method, but it allows you to limit a max amount of variables;
  • LogicExpression nextEqual(LogicExpression exp) alters the expression using propositional logic transformation rules;
  • LogicExpression nextNotEqual(LogicExpression exp) generates a not equal expression to the passed one;
  • LogicExpression nextNotEqual(LogicExpression exp, int maxVarsNumber) does the same as the nextNotEqual method with limitation of a max amount of variables.

Also, there are few additional classes in the library:

  • ExpressionPart represents a single part of a logic expression(bracket, operation, operand ect.);
  • EOperand is one of the ExpressionPart derived classes, represents a particular operand in logic expression, there's a boolean "value" property that's used in calculate methods;
  • TruthTable represents truth table for a particular logic expression, contains method isTautology() for its further analyzying.