| Let F be an arbitrary family of subsets of U and f be a mapping: F→{0,1}, how can we tell whether fz=f for some subset Z of U and how can we construct this Z (or the equivalence class of such Zs)? Here fz:?T∈F,(?).This problem was recognized by D. G. Kendall and the largest element of such Z' s had been established at the same time. In this paper, we shall obtain a class of the minimums and a complete consequence of such Z's by means of F-atom, contacta-bility and relation equation. |
