Hi everyone:

I have a general question about simplifying a k-map that includes some don't care conditions.

My question is: when simplifying a k-map should I place greater importance on making groups of just the 'ones' (and not the don't care variables) and having two groups overlap or on using the 'ones' and the don't care variables and having the groups not overlap at all?

Perhaps this will make it a little more clear.

I have to simplify a sum of products expression using a k-map; I've got it down to three groups of two variables (i.e. three groups like 11,1X,etc on the k-map). If I use the don't care terms, none of the groups overlap. But it is possible just to use the ones (minterm values) to make the three groups but two of the three groups would share a one in this case.

Is either solution more correct than the other? Please advise.

 

You don't necessarily have to overlap the groups. Your main target is to come up with as few terms with as few component in each term, as possible. If that process goes through overlapping groups with Don't Care terms, so be it (it usually does though).

 

Thanks for the reply Georacer!