Says whether to search literals with higher fanin depths
when looking for a pairing for a given literal. Tends
to find more reductions, may take somewhat longer.
If no reducing pairing is found for the first literal of
a supergate, says whether to search for a pairing for the
next literal before defaulting to pairing it with the first
literal. Tends to find more reductions but reduce the network
depth less and take somewhat longer.