Given let , , and be the number of ways of partitioning the set into non-empty subsets, cycles and lists, respectively, with each block having cardinality in . We refer to these as the -restricted Stirling numbers of the second and first kind and the -restricted Lah numbers, respectively. Note that the classical Stirling numbers of the second kind and first kind, and Lah numbers are , ${n \brack k} = {n \brack k}{} L(n,k) = L(n,k){}$, respectively. The matrices , and have inverses , and respectively. The inverse matrices , $[{n \brack k}R]^{-1}{n,k \geq 1}[L(n,k)R]^{-1}{n,k \geq 1}$ exist if and only if . We express each entry of each of these matrices as the difference between the cardinalities of two explicitly defined families of labeled forests. In particular the entries of $[{n \brace k}{[r]}]^{-1}{n,k \geq 1}$ have combinatorial interpretations, affirmatively answering a question of Choi, Long, Ng and Smith from 2006. If and if for all with odd and , we have , we additionally show that each entry of $[{n \brace k}R]^{-1}{n,k \geq 1}[{n \brack k}R]^{-1}{n,k \geq 1}[L(n,k)R]^{-1}{n,k \geq 1}$ is up to an explicit sign the cardinality of a single explicitly defined family of labeled forests. Our results also provide combinatorial interpretations of the th Whitney numbers of the first and second kinds of , the poset of partitions of that have each part size congruent to mod .

生成讲解博客的中文版本

生成AI智能校验的中文版本