Methods and systems improve mapping of LUT based FPGAs. In some embodiments, a topological sort is performed on a network to be mapped, whereby the network is represented as a Directed Acyclic Graph. The system locates feasible reconvergent paths existing from transitive fan-ins of individual nodes using a Reconvergent Path Locator for replicating fan-outs of the nodes in the DAG, and therefore improves the number of LUTs and the time consumed in the mapping process.