Collectanea Mathematica ( IF 1.1 ) Pub Date : 2021-01-06 , DOI: 10.1007/s13348-020-00312-3 Abed Abedelfatah
Let \(S=K[x_1,\ldots ,x_n]\), where K is a field, and \(t_i\) denotes the maximal shift in the minimal graded free S-resolution of the graded algebra S/I at degree i. In this paper, we prove:
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If I is a monomial ideal of S and \(a\ge b-1\ge 0\) are integers such that \(a+b\le \mathrm {proj\,dim}(S/I)\), then
$$\begin{aligned} t_{a+b}\le t_a+t_1+t_2+\cdots +t_b-\frac{b(b-1)}{2}. \end{aligned}$$ -
If \(I=I_{\Delta }\) where \(\Delta \) is a simplicial complex such that \(\dim (\Delta )< t_a-a\) or \(\dim (\Delta )< t_b-b\), then
$$\begin{aligned} t_{a+b}\le t_a+t_b. \end{aligned}$$ -
If I is a monomial ideal that minimally generated by \(m_1,\ldots ,m_r\) such that \(\frac{{{\,\mathrm{lcm}\,}}(m_1,\ldots ,m_r)}{{{\,\mathrm{lcm}\,}}(m_1,\ldots ,\widehat{m}_i,\ldots ,m_r)}\notin K\) for all i, where \(\widehat{m}_i\) means that \(m_i\) is omitted, then \(t_{a+b}\le t_a+t_b\) for all \(a,b\ge 0\) with \(a+b\le \mathrm {proj\,dim}(S/I)\).
中文翻译:
关于合酶的亚可加性条件的一些结果
让\(S = K [X_1,\ ldots,x_n] \) ,其中ķ是一个字段,和\(t_i \)表示在最小分级自由的最大移位小号渐变代数的-分辨率小号/我在程度我。在本文中,我们证明:
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如果I是S的单项式理想并且\(a \ ge b-1 \ ge 0 \)是使得\(a + b \ le \ mathrm {proj \,dim}(S / I)\)的整数,则
$$ \ begin {aligned} t_ {a + b} \ le t_a + t_1 + t_2 + \ cdots + t_b- \ frac {b(b-1)} {2}。\ end {aligned} $$ -
如果\(I = I _ {\ Delta} \)其中\(\ Delta \)是一个简单复数,则\(\ dim(\ Delta)<t_a-a \)或\(\ dim(\ Delta)<t_b -b \),然后
$$ \ begin {aligned} t_ {a + b} \ le t_a + t_b。\ end {aligned} $$ -
如果我是\(m_1,\ ldots,m_r \)最小生成的单项式理想,这样\(\ frac {{{{\,\ mathrm {lcm} \,}}(m_1,\ ldots,m_r)} { {{\,\ mathrm {lcm} \,}}(m_1,\ ldots,\ widehat {m} _i,\ ldots,m_r)} \ notin K \)对于所有i,其中\(\ widehat {m} _i \)装置,其\(M_I \)被省略,然后\(T_ {A + b} \文件T_A + T_B \)对所有\(A,b \ GE 0 \)与\(A + b \文件\ mathrm {proj \,dim}(S / I)\)。