Google self-describes network-opt as, " a C++ library that supports the optimization of network topologies. Using sophisticated techniques for combinatorial search, this algorithm can efficiently construct instances from a family of so-called series-parallel networks that commonly arise in electrical and telecommunications applications. For example, given 15 1-Ω resistors and a target resistance of π Ω, our tool can produce a circuit that achieves six digits of precision. "
Google briefly announced Network-Opt via their Google Open-Source Blog . That blog post cites a Google Research paper on the matter of search strategies for topological network optimization.
Network-Opt is hosted on GitHub .