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License: MIT Build Status Gitter


Copyright 2024 Tomáš Kolárik
Copyright 2023 Martin Blicha
Copyright 2019 Antti Hyvarinen
Copyright 2009 Roberto Bruttomesso

Project page:

OpenSMT is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

OpenSMT2 is an SMT solver written in C++. It supports reading files in SMT-LIB2 format and the theories QF_UF, QF_RDL, QF_IDL, QF_LRA, QF_LIA, QF_UFLRA, QF_UFLIA and QF_AX. The system also provides an API; the distribution includes a minimal example how to use the API.

Building from source

To build the system from the source code repository, you need a C++17 compliant compiler and the following libraries and headers installed:

In addition, the smtlib2 parser uses flex and bison.

OpenSMT2 uses CMake as a build system generator. We use a wrapper Makefile (i.e. GNU Make build system) that allows straightforward building and installing of OpenSMT2.

To configure and build the project, run the following command inside the OpenSMT2 directory:

$ make

This will run cmake -B <build_dir> and cmake --build <build_dir>. The default <build_dir> is build, but it can be changed using the command line option RELEASE_BUILD_DIR, for example: make RELEASE_BUILD_DIR=build-release.

If the command is not run for the first time, it only rebuilds the sources that are not up-to-date. In the case the <build_dir> was removed, it creates it again.

For better interactive experience from shell, OpenSMT can be linked against the BSD-licensed line-editing library Editline Library. To do so, run the following instead of the command above:


The option CMAKE_FLAGS may be used for any additional arguments to be passed to cmake -B <build_dir>. Similarly, the option CMAKE_BUILD_FLAGS may be used for any additional arguments to be passed to cmake --build <build_dir>.

Changing build type

The default build type is Release and make is in fact just an alias to make release. In order to build in Debug mode, use

$ make debug

In this case, options that are related to debug build type should use the *DEBUG* variants instead of *RELEASE*. For example DEBUG_BUILD_DIR=<build_dir>. The default <build_dir> in debug mode is build-debug.

One can also build a parallel version of OpenSMT which can be used with SMTS:

$ make parallel

or to make the corresponding debug type: make parallel-debug.

In order to build all types, run make all.

Restricting components to build

By default, when building OpenSMT, an executable, a static library, and a shared library are created. However, in certain circumstances, it is desirable not to build components you do not need. In these instances, you turn off building components:

  • Passing CMAKE_FLAGS=-DBUILD_STATIC_LIBS:BOOL=OFF will turn off building the static archive for OpenSMT (libopensmt2.a)

  • Passing CMAKE_FLAGS=-DBUILD_SHARED_LIBS:BOOL=OFF will turn off building the shared library for OpenSMT (

  • Passing CMAKE_FLAGS=-DBUILD_EXECUTABLES:BOOL=OFF will turn off building the OpenSMT executable (opensmt)

Given how the opensmt executable is built, you cannot build the executable (i.e., with the default value of -DBUILD_EXECUTABLES:BOOL=ON) with the static archive off (i.e., with -DBUILD_STATIC_LIBS:BOOL=OFF).

Clearing the build

In case one for example needs to rebuild the project from scratch, it can be removed at first:

make clean

(or make clean-release) and then built again with make (or make release). In the case of debug mode, one must run make clean-debug and make debug. It works the same way with *-parallel*. To remove all, run make clean-all.

Unit tests

If you have cmake version 3.11 or higher, the build system will construct unit tests. These are available through

$ make test

(or make test-debug, make test-parallel, make test-all).

Installing OpenSMT2

As long as you haven't disabled building them, the path to the OpenSMT executable is <build_dir>/opensmt, the OpenSMT libraries are located in <build_dir>/lib.

To install OpenSMT into your system simply run:

$ make install

(or make install-release). This runs cmake --install <build_dir>. The install directory can be customized using option INSTALL_DIR=<install_dir>. The default is /usr/local. In such a case, the command above may be neccesary to run with sudo. The default build to be installed is Release. To install the Debug build instead, use make install-debug. To install the parallel variants, use the corresponding *-parallel* rules.

The option INSTALL_DIR may used with all make [release|debug] and make install[-release|-debug]. In the case of the build rules, the <install_dir> is configured within the build directory and is used each time make install[-release|-debug] is used without the additional option INSTALL_DIR. In the case of the install rules, the <install_dir> overrides the previously configured one. The above works the same way with the corresponding *parallel* rules.

Option CMAKE_INSTALL_FLAGS may be used for any additional arguments to be passed to cmake --install <build_dir>.

The command installs the executable binary into the folder <install_dir>/bin, the library into the folder <install_dir>/lib and puts the necessary header files into the folder <install_dir>/include/opensmt.


Build and install with the default values (assuming that writing into /usr/local directory requires root priviledges):

make && sudo make install

Build Release and install into a local directory local_dir:

make release INSTALL_DIR=local_dir && make install-release

Build Debug and install it into a local directory local_dir-debug:

make debug INSTALL_DIR=local_dir-debug && make install-debug

Build (and configure) with the default values but install into local_dir:

make && make install INSTALL_DIR=local_dir

Build and configure to install into local_dir and install there, but also perform another installation into local_dir2:

make INSTALL_DIR=local_dir && make install && make install INSTALL_DIR=local_dir2

Capabilities and usage examples

OpenSMT is an SMT solver, it decides satisfiability of logical formulas in fragments of first-order logic. The input format is SMT-LIB2 and OpenSMT supports quantifier-free SMT-LIB logics, namely any combination of arrays, uninterpreted functions and linear arithmetic or difference logic over reals or integers, both in a single-query and an incremental mode. The exception is that the combination of reals and integers is not supported. To streamline upstream usage, OpenSMT supports ALL as an argument to set-logic command. This is an alias for QF_AUFLIRA. Note, however, that while this allows users to specify problems over reals or integers, the restriction that their combination is not allowed still stands!

To run OpenSMT on a SMT-LIB2 file (.smt2) simply pass the path to the file as an argument to the executable:

$ opensmt test.smt2

It is also possible to run OpenSMT without any arguments, in which case it reads the input from the standard input.

Other engines

OpenSMT supports multiple SMT solving approaches. By the default it uses CDCL(T) with VSDIS decision heuristic. But it can also utilize Lookahead, possibly with picky heuristic based on VSDIS score. Those engines can be enabled by using following config:

(set-option :pure-lookahead true)


(set-option :picky true)


OpenSMT supports a range of interpolation algorithms for propositional logic, linear real arithmetic, and uninterpreted functions with equality.

When using OpenSMT as an executable, interpolation is off by default. It can be enabled by passing -i option to the executable, or by setting the SMT-LIB option produce-interpolants in the input file before the (set-logic) command.

(set-option :produce-interpolants 1)

When using OpenSMT as a library, the option needs to be set in SMTConfig before Opensmt object is created, see this example.

Interpolation is supported for SMT-LIB logics QF_UF, QF_LRA, and QF_LIA in both single-query and incremental mode. An example of how SMT-LIB2 file can be extended to instruct OpenSMT to compute interpolants can be found here.


If you have questions, bug reports, or feature requests, please refer to our GitHub issue tracker or send us an email to, or