One clarification dsantos,Originally posted in cdnusers.org by grasshopper
Most tools will use ALL arcs, and take the max delay of them(min for hold checking). If, however, one of the inputs of the gate was a constant(hard-wired or case analysis), then arcs whose "COND" function resolved to 0 are disabled. Also, if the constants on the gate inputs narrow the choice of COND expressions down to a single one, then the default "COND-less" arc is disabled. Hope this helps.