Are functional depencies with boolean conditions a thing?

Suppose we have a relation R(A, B, C) with the FD A -> B. Let's say that, for two tuples t and u in R, if both t[C] and u[C] satisfy a boolean condition - say less than a constant C - then t[B] = u[B]. Does this constitute a functional dependency? On a more practical sense, how to normalize this relation and eliminate the clear redundancy in R(A, B, C) and allow for lossless joins?