python中的排列，有一个扭曲

I have a list of objects (for the sake of example, let's say 5). I want a list of some of the possible permutations. Specifically, given that some pairs are not together, and some triples don't make sandwiches, how can I generate all other permutations? I realize that I generate all of them first and check that they work, but I think it would be faster to not even consider the pairs and triples that don't work.I have a list of objects (for the sake of examp