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I'm trying to turn on unsat core generation, using Z3 4.3.0 and the .NET API.

Calling context.UpdateParamValue("unsat_core", "true") throws an exception with the message "Error setting 'unsat_core', reason: unknown option".

Checking context.SimplifyParameterDescriptions lists only these parameters:

(:ite-extra-rules, :flat, :elim-and, :local-ctx, :local-ctx-limit, :blast-distinct, :som, :som-blowup, :hoist-mul, :hoist-cmul, :algebraic-number-evaluator, :mul-to-power, :expand-power, :expand-tan, :max-degree, :eq2ineq, :sort-sums, :gcd-rounding, :arith-lhs, :elim-to-real, :push-to-real, :elim-rem, :udiv2mul, :split-concat-eq, :bit2bool, :blast-eq-value, :elim-sign-ext, :hi-div0, :mul2concat, :expand-select-store, :sort-store, :max-memory, :max-steps, :push-ite-arith, :push-ite-bv, :pull-cheap-ite, :cache-all)

This is related to a previously asked question which didn't seem to get a conclusive answer.

Community
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Steven Woodhouse
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1 Answers1

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The exact form the configuration needs to take depends on which parts of Z3, and which version is being used. The SimplifyParameterDescriptions are only for the simplifier (either calls to the Simplify tactic, or Expr.Simplify). Unsat-core generation needs to be enabled either on the Context (via it's constructor and option unsat_core), or via the parameters of a Goal (see Context.MkGoal).

I can't test it where I am right now, but I think the old version (master/4.3.0) used the same parameter name in upper case. Newer versions (i.e., the unstable branch) also have a function for setting global parameters in Global.SetParamValue. Sorry about the confusion, but the parameter setting infrastructure was completely replaced since the last master release.

Christoph Wintersteiger
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  • UNSAT_CORE doesn't work, but looking through the C++ source it looks like DISPLAY_UNSAT_CORE might be what I want? I still can't get an unsat core however, because I do not know how to name an assertion. `AssertAndTrack` does not exist in 4.3.0, and I don't understand the workaround with "answer literals" described [here](http://stackoverflow.com/questions/14560745/unsatisfiable-cores-in-z3-python). – Steven Woodhouse Aug 12 '14 at 09:40
  • No worries, by switching to the nightly build and using the parameter `unsat_core` and calling `AssertAndTrack` I was able to get it to work. – Steven Woodhouse Aug 12 '14 at 12:40