NVIDIA cuOpt is a GPU-accelerated optimization solver library covering linear programming (LP), mixed-integer programming (MIP), quadratic programming (QP), second-order cone programming (SOCP), and vehicle routing problems (VRP, PDP, TSP). The codebase is predominantly an application: it provides multiple deployment forms—a C++ shared library, Python bindings (Cython), a Java JNI interface, a CLI tool (`cuopt_cli`), a gRPC server for remote solves, and a FastAPI-based HTTP server (`cuopt_server`). It also includes comprehensive CI/CD pipelines, benchmarks, and documentation. However, it exhibits a hybrid nature due to its strong research character: advanced algorithmic innovations (e.g., primal-dual hybrid gradient with adaptive step sizing, novel MIP presolve techniques, lattice propagation, deterministic parallel branch-and-bound, SIMD-accelerated MPS parsing, and diversity-based routing heuristics) are deeply embedded in the core solvers. The system is architected as a layered monolith: common utilities and linear algebra form the base, solver-specific modules (PDLP, dual simplex, barrier, branch-and-bound, routing heuristics) sit above, and language bindings and server endpoints wrap the C++ core. Key data flows include parsing MPS/LP files or building problems programmatically, dispatching to the appropriate GPU solver, and retrieving solutions via C structs, Python objects, or protobuf messages. External dependencies include CUDA, cuSPARSE, RMM, NCCL, gRPC, Protobuf, and optionally PaPILO for presolve. The repository is actively maintained with frequent commits and nightly CI, though the presence of deprecated modules and experimental features indicates moderate technical drift.
This repository is the COIN-OR Branch and Cut (Cbc) solver, a mature, production-grade mixed-integer linear programming (MIP) solver written in C++. The core engine implements branch-and-cut using LP relaxations, cut generation (via Cgl library), branching rules, and heuristics. The architecture is object-oriented with well-defined abstractions for branching objects, heuristics, cut generators, node selection, and tree management. Key entry points include the CbcModel class for programmatic use, the CbcMain0/CbcMain1 functions for command-line execution, and a comprehensive C API (Cbc_C_Interface.h) for embedding in other languages. The codebase is large (hundreds of source files) and includes numerous specialized heuristics (dive variants, RINS, DINS, feasibility pump, local search, etc.), branching strategies (pseudo-cost, SOS, clique, N-way, orbital), and preprocessing techniques. It integrates with the broader COIN-OR ecosystem (Clp, Osi, CoinUtils, Cgl) and supports parallel execution via threads. Despite its age, the code shows active development with recent additions (conflict graph features, branching ranker, configurable dive heuristics) and a new output framework. However, it carries legacy artifacts: autotools build system, an Attic/ directory with deprecated code, extensive conditional compilation (#ifdef blocks), and some experimental or unfinished features.