1. A method comprising: determining a spacing for each of a plurality of edges comprising one or more features in a photolithographic design, said plurality of edges having at least a partially predictable layout; generating a bridge structure for the plurality of edges based on the spacings and the predictable layout, each bridge of the bridge structure to connect one of the plurality of edges to an edge of a neighboring feature; and providing the features and the bridge structure for a phase assignment, said phase assignment to assign features at opposite ends of each of said bridges to opposite phases.