FsZ3

A simple DSL to solve SMT problems using Z3 API in F#.

git clone https://github.com/haf/FsZ3.git
bundle
bundle exec rake

Purpose

Z3 is a high-performance theorem prover being developed at Microsoft Research. Z3 has an official .NET API written in C#, but it is too verbose and not F#-friendly. This project aims at providing a simple API to:

do constraint solving,
check satisfiability of logical formulas, and
prove theorems,

in a concise way in F#.

FsZ3 is inspired by Z3Py and along the same line of Scala^Z3 and SBV.

Examples

For instance, here is a very simple constraint solving problem in FsZ3:

// Create 3 integer variables
let dog = Int("dog")
let cat = Int("cat")
let mouse = Int("mouse")

Z3.Solve(dog >=. 1I,   // at least one dog
         cat >=. 1I,   // at least one cat
         mouse >=. 1I, // at least one mouse
         // we want to buy 100 animals
         dog + cat + mouse =. 100I,
         // We have 100 dollars (10000 cents):
         // dogs cost 15 dollars (1500 cents),
         //   cats cost 1 dollar (100 cents), and
         //   mice cost 25 cents
         1500I * dog + 100I * cat + 25I * mouse =. 10000I)

Take a look at Examples for an extensive set of examples.

Setup / Installation

64 bit mono
albacore
Run bundle exec rake and check out ./src/Examples

Current limitations

Poor support for uninterpreted functions. You need explicit type annotations and there is no way to detect inconsistencies between arguments in a type-safe way.
Limited support for array theory. It suffers from the same symptoms as uninterpreted functions.
Bad coding habits. The code base currently uses too many type constraints.
Support for quantifiers would be hard. Maybe it isn't the correct way to go forward.
The syntax isn't very concise. It might be better to lean towards declarative style.

TODO

Check correctness of examples carefully.
Implement other theories: Arrays, Datatypes and Quantifiers.
Rearrange modules; many functions are in wrong places.
Rewrite ToString() for pretty-printing.
Standardize the use of %A and %O.

License

The MIT license

dungpa / Z3Fs