Basic vs compound condition coverage

I'm trying to get my head around the differences between these 2 coverage criterias and I can't work out how they differ. I think I'm failing to understand exactly what a decision coverage is. My software testing textbook states that compound decision coverage can be costly (2^n combinations for n basic conditions).

I would have thought basic condition coverage would be costlier.

Consider a && b && c && d && e. My understanding is that in basic condition coverage, each of these atomic variables have to have the value TRUE and FALSE in a test case for the test case to be have basic condition adequacy - that's 32 different test cases.

So what is the actual difference, and what is referred to as a "basic condition". In the example above, is a a basic condition?

Thanks.