If G is a finite abstract simplicial complex and K is a subcomplex of G and U=G-K is the open complement of K in G, the Betti vectors of K and U and G satisfy the inequality b(G) less or equal b(K)+b(U).

翻译：若G为有限抽象单纯复形，K为G的子复形，且U=G-K是K在G中的开补集，则K、U与G的贝蒂向量满足不等式b(G) ≤ b(K)+b(U)。