NanoByte.SatSolver 0.2.0

NanoByte SAT Solver is a DPLL Boolean Satisfiability Solver for .NET.

You need to choose the underlying type to use for Literals in Boolean Formulas. This will often be int or string but you can also use any other type that implements the IEquatable<T> interface. You can then create an instance of Solver<T>:

var solver = new Solver<string>();

The library enables you to express Boolean Formulas using implicit casting and operators for human-friendly sample and test code:

Literal<string> a = "a", b = "b", c = "c", d = "d";
var formula = (a | b) & (!a | c) & (!c | d) & a;

For constructing Formulas at run-time you can use a collection-like interface instead:

var formula = new Formula<string>
{
    new Clause<string> {Literal.Of("a"), Literal.Of("b")},
    new Clause<string> {Literal.Of("a").Negate(), Literal.Of("c")},
    new Clause<string> {Literal.Of("c").Negate(), Literal.Of("d")},
    new Clause<string> {Literal.Of("a")}
};

Finally, you can use the solver to determine whether a Formula is satisfiable:

bool result = solver.IsSatisfiable(formula);

When the Solver needs to choose a Literal to assign a truth value to during backtracking, it simply picks the first unset Literal from the list. You can replace this with your own domain-specific logic for better performance by deriving from Solver<T> and overriding the ChooseLiteral() method.