Two birds A and B are said to /agree/ on x if their responses are the same: Ax = Bx
A bird A is called /agreeable/ if for every bird B there is at least one bird x on which A and B agree, or in other words: Ax = Bx
Here's a variant of problem 1:
We're given the composition condition (C1), but not that there's a mockingbird, instead we know that there is an agreeable bird A
Is it enough to guarantee that every bird is fond of at least one bird?