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SRI-CSL
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#### Description

The Yices SMT Solver

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# Yices 2

Yices 2 is a solver for Satisfiability Modulo Theories (SMT) problems. Yices 2 can process input written in the SMT-LIB language, or in Yices' own specification language. We also provide a C API and bindings for Python, Go, and OCaml.

This repository includes the source of Yices 2, documentation, tests, and examples.

## Simple Examples

Here are a few typical small examples that illustrate the use of Yices using the SMT2 language.

#### Linear Real Arithmetic

```;; QF_LRA = Quantifier-Free Linear Real Arithmetic
(set-logic QF_LRA)
;; Declare variables x, y
(declare-fun x () Real)
(declare-fun y () Real)
;; Find solution to (x + y > 0), ((x < 0) || (y < 0))
(assert (> (+ x y) 0))
(assert (or (< x 0) (< y 0)))
;; Run a satisfiability check
(check-sat)
;; Print the model
(get-model)
```

Running Yices on the above problem gives a solution ```

yices-smt2 lra.smt2 sat (= x 2) (= y (- 1)) ```

#### Bit-Vectors

```;; QF_BV = Quantifier-Free Bit-Vectors
(set-logic QF_BV)
;; Declare variables
(declare-fun x () (_ BitVec 32))
(declare-fun y () (_ BitVec 32))
;; Find solution to (signed) x > 0, y > 0, x + y < x
(assert (bvsgt x #x00000000))
(assert (bvsgt y #x00000000))
(assert (bvslt (bvadd x y) x))
;; Check
(check-sat)
;; Get the model
(get-model)
```

Running Yices on the above problem gives

```> yices-smt2 bv.smt2
sat
(= x #b01000000000000000000000000000000)
(= y #b01000000000000000000000000000000)
```

#### Non-Linear Arithmetic

```;; QF_NRA = Quantifier-Free Nonlinear Real Arithmetic
(set-logic QF_NRA)
;; Declare variables
(declare-fun x () Real)
(declare-fun y () Real)
;; Find solution to x^2 + y^2 = 1, x = 2*y, x > 0
(assert (= (+ (* x x) (* y y)) 1))
(assert (= x (* 2 y)))
(assert (> x 0))
;; Check
(check-sat)
;; Get the model
(get-model)
```

Running Yices on the above problem gives

```sat
(= x 0.894427)
(= y 0.447214)
```

## Installing Prebuilt Binaries

Currently you can install Yices either using Homebrew or Apt.

#### Homebrew

Installing on Darwin using homebrew can be achieved via:

```brew install SRI-CSL/sri-csl/yices2
```
This will install the full mcsat-enabled version of Yices, including dynamic library and header files.

#### Apt

To install Yices on Ubuntu or Debian, do the following:

```sudo add-apt-repository ppa:sri-csl/formal-methods
sudo apt-get update
sudo apt-get install yices2
```
This will install the executables. If you also need the Yices library and header files, replace the last step with:
```sudo apt-get install yices2-dev
```

## Building From Source

#### Prerequisites

To build Yices from the source, you need:

• gperf version 3.0 or newer
• the GMP library version 4.1 or newer

• other standard tools: make (gnumake is required), sed, etc.

To build the manual, you also need:

• a latex installation
• the latexmk tool

To build the on-line documentation, you need to install the Sphinx python package. The simplest method is:

```sudo pip install sphinx
```

Sphinx 1.4.x or better is needed.

#### Quick Installation

Do this:

```autoconf
./configure
make
sudo make install
```

This will install binaries and libraries in

`/usr/local/`
. You can change the installation location by giving option
`--prefix=...`
to the
`./configure`
script.

`doc/COMPILING`
.

#### Support for Non-Linear Arithmetic and MC-SAT

Yices supports non-linear real and integer arithmetic using a method known as Model-Constructing Satisfiability (MC-SAT), but this is not enabled by default. The MC-SAT solver also supports other theories and theory combination. We are currently extending it to handle bit-vector constraints.

If you want the MC-SAT solver, follow these instructions:

1. Install SRI's library for polynomial manipulation. It's available on github.

2. Install the CUDD library for binary-decision diagrams. We recommand using the github distribution: https://github.com/ivmai/cudd.

3. After you've installed libpoly and CUDD, add option

`--enable-mcsat`
to the configure command. In details, type this in the toplevel Yices directory:
```autoconf
./configure --enable-mcsat
make
sudo make install
```
1. You may need to provide
`LDFLAGS/CPPFLAGS`
if
`./configure`
fails to find the libpoly or CUDD libraries. Other options may be useful too. Try
`./configure --help`
to see what's there.

The Yices library is not thread safe by default, if you need a re-entrant version:

```autoconf
make
sudo make install
```

If configured with

`--enable-thread-safety`
the Yices library will be thread safe in the following sense: as long as the creation and manipulation of each context and each model is restricted to a single thread, there should be no races. In particular separate threads can create their own contexts, and manipulate and check them without impeding another thread's progress.

NOTE:

`--enable-mcsat`
and
`--enable-thread-safety`
are currently incompatible.

#### Windows Builds

We recommend compiling using Cygwin. If you want a version that works natively on Windows (i.e., does not depend on the Cygwin DLLs), you can compile from Cygwin using the MinGW cross-compilers. This is explained in doc/COMPILING.

#### Documentation

To build the manual from the source, type

```make doc
```
This will build
`./doc/manual/manual.pdf`
.

Other documentation is in the

`./doc`
directory:
• `doc/COMPILING`
explains the compilation process and options in detail.
• `doc/NOTES`
gives an overview of the source code.
• `doc/YICES-LANGUAGE`
explains the syntax of the Yices language, and describes commands, functions, and heuristic parameters.

To build the Sphinx documentation:

```cd doc/sphinx
make html
```

This will build the documentation in build/html (within directory doc/sphinx). You can also do:

```make epub
```
and you'll have the doc in
`build/epub/Yices.epub`
.

## Getting Help and Reporting bugs

For further questions about Yices, please contact us via the Yices mailing lists [email protected] This mailing list is moderated, but you do not need to register to post to it. You can register to this mailing list if you are interested in helping others.

Please submit bug reports through GitHub issues. Please include enough information in your bug report to enable us to reproduce and fix the problem. This is an example of a good report:

I am experiencing a segmentation fault from Yices. The following is a small test case that causes the crash. I am using Yices 2.4.1 on x86_64 statically linked against GMP on Ubuntu 12.04.

This is an example of a poor bug report:

I have just downloaded Yices. After I compile my code and link it with Yices, there is a segmentation fault when I run the executable. Can you help?

Please try to include answers to the following questions: * Which version of Yices are you using? * On which hardware and OS? * How can we reproduce the bug? If possible, include an input file or program fragment.