74181 from max+plus II.

I was told that notation xN x_L ~x inside the chip with another invert bubble is not allowed.That is,you should either use one invert bubble,or use suffix N/_L to represent negative active input.

Is altera wrong and the invert bubble should be removed?

thanks.

 

This is a difficult IC to reduce to only inputs and outputs. See if this paper helps - www.pld.ttu.ee/.../Unveiling the ISCAS-85 Benchmarks - A Case Study in Reverse .pdf