Microsoft Research claims that Z3 is the world’s fastest theorem prover. Z3 is designed to be a low-level tool for other applications, it is not meant to stand-alone. With its host of theorem provers, it is used by numerous projects including Spec#/Boogie, Pex, Yogi, Vigilante, SLAM, F7, SAGE, VS3, FORMULA, and HAVOC.
Using Z3’s .NET API, one can encode theorems using an object-orientated style. However the example in the Z3 Tutorial demonstrates that even small problems can be quite tedious to code. Bart De Smet greatly simplified this by wrapping the OO-style API with a query-style API called LINQ to Z3. Below is an example that accompanied Bart De Smet’s Channel 9 interview.
var theorem = from t in ctx.NewTheorem<Symbols<int, int, int, int, int>>()
where t.X1 - t.X2 >= 1
where t.X1 - t.X2 <= 3
where t.X1 == (2 * t.X3) + t.X5
where t.X3 == t.X5
where t.X2 == 6 * t.X4
select t;
var solution = theorem.Solve();
Console.WriteLine("X1 = {0}, X2 = {1}, X3 = {2}, X4 = {3}, X5 = {4}",
Support for Z3 primarily available on Windows, but there is a Linux version of Z3. Z3 is released for non-commercial use under the “Microsoft Research License Agreement”. You can play with an on-line version of Z3 on RiSE4fun.