In a Gray code only one bit can change state to advance to the next code in the sequence. There are various forms but here is one:

000

001

011

010

110

111

101

100

By using a Gray code on the toroidal Karanugh map and plotting your true states of your Boolean equation, should any two true states be adjacant then one of the variables is irrelevant. That's because it changed state and did not affect the outcome.

Four adjacent true points mean two irrelevant variables.

And, of course, the open sequares are the inverse.

It's much easier for reduction than using a Vietsch diagram and measuring

Yes I know what Gray codes are; but still, finding 'adjacent' areas is still a very

visual process; the Q-McK algorithm simply produces tables of the terrms of

disjunctive normal forms and produces a reduced table (if possible) etc. etc.

until no further reduction is possible (it tries to find 'resolutions' just like those

Gray code numbers). The Karnaugh maps make me dizzy above three (four?)

variables; the Q-McK algorithm doesn't care about many variables are used.

Doing that by hand is a boring and error prone process.

I agree Karnaugh maps are more fun to work (play?) with for humans using just

a few variables.

kind regards,

Jos