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枚举强制和强强制(0,1)-矩阵

Enumerating forcing and strongly forcing (0,1)-matrices

Lei Cao, Jesse Geneson

arXiv 2608.17294首次发表:更新:

AI 中文总结

该研究分析强Q-强制与普通强制(0,1)-矩阵的数量,证明强Q-强制矩阵数量的下界,细化权重计数,推导两类强制矩阵数量的乘积界,明确等号成立条件。

AI 中文摘要

设Q为非零s×t阶(0,1)-模式,m≥s且n≥t。一个m×n阶矩阵是强Q-强制的,当且仅当每个1-元素都属于一个等于Q的s×t阶子矩阵。记F*(m,n,Q)为这类矩阵的数量,令H=m-s+1,W=n-t+1,我们证明F*(m,n,Q)≥2^(HW)。设r和c分别为Q的非零行和非零列的数量,等号成立当且仅当(H=1或r=1)且(W=1或c=1)。因此,所有非零s×t阶模式的最小值为2^(HW),当H,W>1时,该最小值恰好由单元素模式达到;每个固定非零模式的平方增长率均为1。我们还按权重细化计数:若o(Q)为Q的1-元素数量,则最小正权重o(Q)对应的强Q-强制矩阵数量为组合数(H+r-1选r)乘以组合数(W+c-1选c);当m与n可比时,对于(0,1)内的每个固定密度,对数增长率为二元熵。对于普通强制,即每个s×t阶子矩阵在规定位置包含Q的1-元素,记F(m,n,Q)为强制矩阵的数量,m(m,n,Q)为其最小权重,我们证明F(m,n,Q)=2^(mn - m(m,n,Q)),且2^(mn - m(m,n,Q)+HW) ≤ F(m,n,Q)F*(m,n,Q) ≤ 2^mn。该乘积下界的等号成立情形与上述强强制下界相同,而上界恰好由单元素模式达到。特别地,乘积至少为2,当且仅当s=m、t=n且Q为全1模式时等号成立。

英文摘要

Let $Q$ be a nonzero $s\times t$ $(0,1)$-pattern, and let $m\ge s$ and $n\ge t$. An $m\times n$ matrix is strongly $Q$-forcing if every $1$-entry belongs to an $s\times t$ submatrix equal to $Q$. Let $F^{*}(m,n,Q)$ count these matrices. Put $H=m-s+1$ and $W=n-t+1$. We prove \[ F^{*}(m,n,Q)\ge 2^{HW}. \] Writing $r$ and $c$ for the numbers of nonzero rows and columns of $Q$, equality holds if and only if \[ (H=1\text{ or }r=1)\qquad\text{and}\qquad(W=1\text{ or }c=1). \] Thus the minimum over all nonzero $s\times t$ patterns is $2^{HW}$, attained exactly by singleton patterns when $H,W>1$, and every fixed nonzero pattern has square growth rate $1$. We also refine the count by weight. If $o(Q)$ is the number of $1$-entries of $Q$, then the number of strongly $Q$-forcing matrices at the minimum positive weight $o(Q)$ is $\binom{H+r-1}{r}\binom{W+c-1}{c}$; at every fixed density in $(0,1)$, the logarithmic growth rate is the binary entropy when $m$ and $n$ are comparable. For ordinary forcing, where every $s\times t$ submatrix contains the $1$-entries of $Q$ in their prescribed positions, let $F(m,n,Q)$ be the number of forcing matrices and let $\mathfrak m(m,n,Q)$ be their minimum weight. We prove \[ F(m,n,Q)=2^{mn-\mathfrak m(m,n,Q)} \quad\text{and}\quad 2^{\,mn-\mathfrak m(m,n,Q)+HW} \le F(m,n,Q)F^{*}(m,n,Q) \le 2^{mn}. \] The lower product bound has the same equality cases as the strong-forcing lower bound above, while the upper product bound is attained exactly by singleton patterns. In particular, the product is at least $2$, with equality exactly when $s=m$, $t=n$, and $Q$ is the all-ones pattern.

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