Based on a completely distributive lattice $L$, degrees of compatible $L$-subsets and compatible mappings are introduced in an $L$-approximation space and their characterizations are given by four kinds of cut sets of $L$-subsets and $L$-equivalences, respectively. Besides, some characterizations of compatible mappings and compatible degrees of mappings are given by compatible $L$-subsets and compatible degrees of $L$-subsets. Finally, the notion of complete $L$-sublattices is introduced and it is shown that the product of complete $L$-sublattices is still a complete $L$-sublattice and the compatible degree of an $L$-subset is a complete $L$-sublattice.
$L$-approximation spaces, compatible $L$-subsets, compatible mappings, complete $L$-sublattices
06B75, 06D10, 06D72