theorem :: BVFUNC14:20
for Y being non empty set
for G being Subset of (PARTITIONS Y)
for A, B, C being a_partition of Y
for z, u being Element of Y st G is independent & G = {A,B,C} & A <> B & B <> C & C <> A & EqClass (z,C) = EqClass (u,C) holds
EqClass (u,(CompF (A,G))) meets EqClass (z,(CompF (B,G)))