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unifier(expression,expression) → assignment
The subroutine unifier takes two expressions as arguments and checks whether the two expressions can be unified. If so, unifier returns the variable assignment; otherwise, it returns false.
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Call: unifier(read('p(X,Y)'),read('p(a,b)'))
Exit: {X:a, Y:b}
Call: unifier(read('p(X,Y)'),read('p(a,a)'))
Exit: {X:a, Y:a}
Call: unifier(read('p(X,X)'),read('p(a,a)'))
Exit: {X:a}
Call: unifier(read('p(a,b)'),read('p(a,b)'))
Exit: {}
Call: unifier(read('p(X,X)'),read('p(a,b)'))
Exit: false
User: unifier(read('p(a,b)'),read('p(X,Y)'))
Exit: false
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Two expressions can be unified if and only of there is a variable assignment that makes them look alike, i.e. the result of applying the variable assignment to the first expression is identical to the result of applying the variable assignment to the second expression.
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