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https://github.com/Z3Prover/z3
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114 lines
4.2 KiB
Python
114 lines
4.2 KiB
Python
# This script illustrates uses of proof replay and proof logs over the Python interface.
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from z3 import *
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example1 = """
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(declare-sort T)
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(declare-fun subtype (T T) Bool)
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;; subtype is reflexive
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(assert (forall ((x T)) (subtype x x)))
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;; subtype is antisymmetric
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(assert (forall ((x T) (y T)) (=> (and (subtype x y)
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(subtype y x))
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(= x y))))
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;; subtype is transitive
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(assert (forall ((x T) (y T) (z T)) (=> (and (subtype x y)
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(subtype y z))
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(subtype x z))))
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;; subtype has the tree-property
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(assert (forall ((x T) (y T) (z T)) (=> (and (subtype x z)
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(subtype y z))
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(or (subtype x y)
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(subtype y x)))))
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;; now we define a simple example using the axiomatization above.
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(declare-const obj-type T)
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(declare-const int-type T)
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(declare-const real-type T)
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(declare-const complex-type T)
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(declare-const string-type T)
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;; we have an additional axiom: every type is a subtype of obj-type
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(assert (forall ((x T)) (subtype x obj-type)))
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(assert (subtype int-type real-type))
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(assert (subtype real-type complex-type))
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(assert (not (subtype string-type real-type)))
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(declare-const root-type T)
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(assert (subtype obj-type root-type))
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"""
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if __name__ == "__main__":
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print("Solve and log inferences")
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print("--------------------------------------------------------")
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# inference logging, replay, and checking is supported for
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# the core enabled by setting sat.euf = true.
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# setting the default tactic to 'sat' bypasses other tactics that could
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# end up using different solvers.
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set_param("sat.euf", True)
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set_param("tactic.default_tactic", "sat")
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# Set a log file to trace inferences
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set_param("sat.smt.proof", "proof_log.smt2")
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s = Solver()
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s.from_string(example1)
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print(s.check())
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print(s.statistics())
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print("Parse the logged inferences and replay them")
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print("--------------------------------------------------------")
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# Reset the log file to an invalid (empty) file name.
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set_param("sat.smt.proof", "")
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# Turn off proof checking. It is on by default when parsing proof logs.
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set_param("solver.proof.check", False)
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s = Solver()
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onc = OnClause(s, lambda pr, clause : print(pr, clause))
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s.from_file("proof_log.smt2")
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print("Parse the logged inferences and check them")
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print("--------------------------------------------------------")
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s = Solver()
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# Now turn on proof checking. It invokes the self-validator.
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# The self-validator produces log lines of the form:
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# (proofs +tseitin 60 +alldiff 8 +euf 3 +rup 5 +inst 6 -quant 3 -inst 2)
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# (verified-smt
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# (inst (forall (vars (x T) (y T) (z T)) (or (subtype (:var 2) (:var 1)) ...
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# The 'proofs' line summarizes inferences that were self-validated.
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# The pair +tseitin 60 indicates that 60 inferences were validated as Tseitin
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# encodings.
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# The pair -inst 2 indicates that two quantifier instantiations were not self-validated
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# They were instead validated using a call to SMT solving. A log for an smt invocation
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# is exemplified in the next line.
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# Note that the pair +inst 6 indicates that 6 quantifier instantiations were validated
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# using a syntactic (cheap) check. Some quantifier instantiations based on quantifier elimination
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# are not simple substitutions and therefore a simple syntactic check does not suffice.
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set_param("solver.proof.check", True)
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s.from_file("proof_log.smt2")
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print("Verify and self-validate on the fly")
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print("--------------------------------------------------------")
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set_param("sat.smt.proof.check", True)
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s = Solver()
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s.from_string(example1)
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print(s.check())
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print(s.statistics())
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print("Verify and self-validate on the fly, but don't check rup")
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print("--------------------------------------------------------")
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set_param("sat.smt.proof.check", True)
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set_param("sat.smt.proof.check_rup", False)
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s = Solver()
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s.from_string(example1)
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print(s.check())
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print(s.statistics())
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