[Haskell-cafe] Haskell SBV Package with Z3

[Levent Erkok]

You're welcome Jun Jie. 

Regarding getting a different counter example: That's perfectly normal. When SMT solvers build models they use random seeds. Furthermore, different versions of the same solver can use different algorithms/heuristics to arrive at the falsifying model. So, it's entirely expected that you get a different counter-example. You can turn the question around, and ask the solver to give you all counter-examples like this:

         allSat $ \x -> \(x::SWord8) -> x `shiftL` 2 .!= x

-Levent. 

On Mar 29, 2013, at 1:42 AM, "J. J. W." <bsc.j.j.w at gmail.com> wrote:

> Dear Levent,
> 
> Thank you for your support. I am very honoured to have the developer of the SBV package to solve my elementary problem. I noticed that the counter-example given by my Z3 differs from the one said on HackageDB: sbv-2.10.
> 
> Code that is on Hackage:
> 
>  Prelude Data.SBV> prove $ forAll ["x"] $ \(x::SWord8) -> x `shiftL` 2 .== x
>    Falsifiable. Counter-example:
>      x = 128 :: SWord8
> 
> My current GHCi output:
> 
> Prelude Data.SBV> prove $ forAll ["x"] $ \(x::SWord8) -> x `shiftL` 2 .== x
> Falsifiable. Counter-example:
>   x = 51 :: SWord8
> (0.02 secs, 1196468 bytes)
> 
> Thank you for your help!
> 
> Yours sincerely,
> 
> Jun Jie
> 
> 
> 2013/3/29 Levent Erkok <erkokl at gmail.com>
>> Hi Jun Jie:
>> 
>> SBV uses some of the not-yet-officially-released features in Z3. The version you have, while it's the latest official Z3 release, will not work.
>> 
>> To resolve, you need to install the "development" version of Z3 (something that is at least 4.3.2 or better). Here're instructions from the Microsoft folks explaining how to get these builds: http://research.microsoft.com/en-us/um/people/leonardo/blog/2013/02/15/precompiled.html
>> 
>> Let me know if you find any issues after you get the latest-development version of Z3 installed.
>> 
>> -Levent.  
>> 
>> 
>> On Thu, Mar 28, 2013 at 10:22 PM, J. J. W. <bsc.j.j.w at gmail.com> wrote:
>>> Dear all,
>>> 
>>> I have a small question regarding the installation of the SBV package. I first installed the SBV 2.10 package with cabal with the following instructions:
>>> 
>>> cabal install sbv
>>> 
>>> Next I installed the Z3 theorem prover and adding the path to my system variables (Windows 7 x64). Next I tested whether I could find it by opening cmd.exe and then typing z3, I get an error message of Z3, so I can safely assume the system can find it. (I added the path to the bin of Z3, I have not included the include directory, I see no reason why I should add a path to this directory, but maybe I am wrong).
>>> 
>>> I ran the program: SBVUnitTests. However it had some errors in the beginning and afterwards a few failures. Having no idea how to fix this, I continued to check whether I can get the SBV to work. So I started to execute the SBV package:
>>> 
>>> ghci -XScopedTypeVariables
>>> ghci> :m Data.SBV
>>> ghci> prove $ \(x::SWord8) -> x `shiftL` 2 .== 4*x
>>> 
>>> Now this should return Q.E.D., however it returned the following:
>>> 
>>> An error occured.
>>> Failed to complete the call to z3
>>> Executable: "C:\\Program Files\\z3-4.3.0-x64\\bin\\z3.exe
>>> Options: /in /smt2
>>> Exit code: 0
>>> Solver output:
>>> ===========================================================
>>> ; :smt.mbqi
>>> ; :pp.decimal_precision
>>> ===========================================================
>>> 
>>> Giving up..
>>> 
>>> It does seems like that the Z3 has a normal output, however not a result. Can someone help me to figure out what I actually did wrong?
>>> 
>>> I am using Z3 version 4.3.0, SBV 2.10 and GHCi 7.4.2
>>> 
>>> Thank you for your help!
>>> 
>>> Yours sincerely,
>>> 
>>> Jun Jie
>>> 
>>> 
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> 
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