1. A computer-implemented method for building binary decision diagrams comprising: traversing a gate-level netlist graph including a plurality of nodes in a depth-first manner using a computer; while traversing the netlist graph, building, using a computer, a binary decision diagram representation of the netlist graph, wherein building the binary decision diagram representation includes building at least one first binary decision diagram for a first input of a node among the plurality of nodes in said netlist graph using one or more second binary decision diagrams for a second input of said node as a don't-care condition; wherein the step of building at least one first binary decision diagram for the first input of the node of said netlist graph using one or more second binary decision diagrams for the second input of said node as a don't-care condition is applied selectively when said at least one first binary decision diagram reaches a predetermined size.