Theory of Computing Systems ( IF 0.6 ) Pub Date : 2021-07-15 , DOI: 10.1007/s00224-021-10053-w V. Arvind 1 , Abhranil Chatterjee 1 , Rajit Datta 2 , Partha Mukhopadhyay 2
Let \({\mathbb {F}}[X]\) be the polynomial ring in the variables X = {x1,x2,…,xn} over a field \({\mathbb {F}}\). An ideal I = 〈p1(x1),…,pn(xn)〉 generated by univariate polynomials \(\{p_{i}(x_{i})\}_{i=1}^{n}\) is a univariate ideal. Motivated by Alon’s Combinatorial Nullstellensatz we study the complexity of univariate ideal membership: Given \(f\in {\mathbb {F}}[X]\) by a circuit and polynomials pi the problem is test if f ∈ I. We obtain the following results.
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Suppose f is a degree-d, rank-r polynomial given by an arithmetic circuit where ℓi : 1 ≤ i ≤ r are linear forms in X. We give a deterministic time dO(r) ⋅poly(n) division algorithm for evaluating the (unique) remainder polynomial f(X)modI at any point \(\vec {a}\in {\mathbb {F}}^{n}\). This yields a randomized nO(r) algorithm for minimum vertex cover in graphs with rank-r adjacency matrices. It also yields a new nO(r) algorithm for evaluating the permanent of a n × n matrix of rank r, over any field \(\mathbb {F}\).
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Let f be over rationals with \(\deg (f)=k\) treated as fixed parameter. When the ideal \(I=\left \langle {x_{1}^{e_{1}}, \ldots , x_{n}^{e_{n}}}\right \rangle \), we can test ideal membership in randomized O∗((2e)k). On the other hand, if each pi has all distinct rational roots we can check if f ∈ I in randomized O∗(nk/2) time, improving on the brute-force \(\left (\begin {array}{cc}{n+k}\\ k \end {array}\right )\)-time search.
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If \(I=\left \langle {p_{1}(x_{1}), \ldots , p_{k}(x_{k})}\right \rangle \), with k as fixed parameter, then ideal membership testing is W[2]-hard. The problem is MINI[1]-hard in the special case when \(I=\left \langle {x_{1}^{e_{1}}, \ldots , x_{k}^{e_{k}}}\right \rangle \).
中文翻译:
由等级、度数和生成器数量参数化的单变量理想隶属度
令\({\mathbb {F}}[X]\)是变量X = { x 1 , x 2 ,..., x n } 中的多项式环在域\({\mathbb {F}}\) . 由单变量多项式\(\{p_{i}(x_{i})\}_{i=1}^{n生成的理想I = 〈p 1 ( x 1 ),…, p n ( x n )〉}\)是一个单变量的理想。受 Alon 的组合 Nullstellensatz 的启发,我们研究了单变量理想隶属度的复杂性:给定\(f\in {\mathbb {F}}[X]\)通过电路和多项式p i问题是测试f ∈ I。我们得到以下结果。
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假设f是由算术电路给出的d阶、r阶多项式,其中ℓ i : 1 ≤ i ≤ r是X中的线性形式。我们给出了一个确定性时间d O ( r ) ⋅poly( n ) 除法算法,用于在任何点评估(唯一的)余数多项式f ( X )mod I \(\vec {a}\in {\mathbb {F}} ^{n}\)。这产生了一个随机的n O ( r )具有秩r邻接矩阵的图中最小顶点覆盖的算法。它还产生了一个新的n O ( r )算法,用于在任何字段\(\mathbb {F}\) 上评估n × n秩为r 的矩阵的永久值。
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令f超过有理数,\(\deg (f)=k\)被视为固定参数。当理想\(I=\left \langle {x_{1}^{e_{1}}, \ldots , x_{n}^{e_{n}}}\right \rangle \),我们可以测试理想随机O ∗ ((2 e ) k ) 中的成员资格。另一方面,如果每个p i都有所有不同的有理根,我们可以在随机O ∗ ( n k /2 ) 时间内检查f ∈ I是否改进了蛮力\(\left (\begin {array}{ cc}{n+k}\\ k \end {array}\right )\) - 时间搜索。
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如果\(I=\left \langle {p_{1}(x_{1}), \ldots , p_{k}(x_{k})}\right \rangle \),以k为固定参数,则理想成员资格测试是 W[2]-hard。当\(I=\left \langle {x_{1}^{e_{1}}, \ldots , x_{k}^{e_{k}}} \right \rangle \)。