LEMON stands for Library for Efficient Modeling and Optimization in Networks. It is a C++ template library providing efficient implementations of common data structures and algorithms with focus on combinatorial optimization tasks connected mainly with graphs and networks.

LEMON is a member of the COIN-OR initiative, a collection of OR related open source projects. You are free to use it in your commercial or non-commercial applications under very permissive license terms.

The project was launched by the Egerváry Research Group on Combinatorial Optimization (EGRES) at the Operations Research Department of the Eötvös Loránd University, Budapest in 2003. Up to this point, the developers of the library work at the Eötvös Loránd University, Budapest and at the Budapest University of Technology and Economics.