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36 lines
843 B
Python
36 lines
843 B
Python
############################################
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# Copyright (c) Microsoft Corporation. All Rights Reserved.
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#
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# all humans are mortal
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# Socrates is a human
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# so Socrates mortal
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############################################
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from z3 import *
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set_param(proof=True)
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Object = DeclareSort('Object')
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Human = Function('Human', Object, BoolSort())
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Mortal = Function('Mortal', Object, BoolSort())
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# a well known philosopher
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socrates = Const('socrates', Object)
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# free variables used in forall must be declared Const in python
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x = Const('x', Object)
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axioms = [ForAll([x], Implies(Human(x), Mortal(x))),
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Human(socrates) == True]
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s = Solver()
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s.add(axioms)
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# classical refutation
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s.add(Mortal(socrates) == False)
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print(s.check()) # prints unsat so socrates is Mortal
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# print(s.proof()) # prints a low level (not readable) proof object.
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