Jin-San Cheng , Kai Jin , Marc Pouget , Junyi Wen , Bingwei Zhang
{"title":"An improved complexity bound for computing the topology of a real algebraic space curve","authors":"Jin-San Cheng , Kai Jin , Marc Pouget , Junyi Wen , Bingwei Zhang","doi":"10.1016/j.jsc.2024.102309","DOIUrl":"10.1016/j.jsc.2024.102309","url":null,"abstract":"<div><p>We propose a new algorithm to compute the topology of a real algebraic space curve. The novelties of this algorithm are a new technique to achieve the lifting step which recovers points of the space curve in each plane fiber from several projections and a weaker notion of generic position. As distinct to previous work, our <em>sweep generic position</em> does not require that <em>x</em>-critical points have different <em>x</em>-coordinates. The complexity of achieving this sweep generic position property is thus no longer a bottleneck in term of complexity. The bit complexity of our algorithm is <span><math><mover><mrow><mi>O</mi></mrow><mrow><mo>˜</mo></mrow></mover><mo>(</mo><msup><mrow><mi>d</mi></mrow><mrow><mn>18</mn></mrow></msup><mo>+</mo><msup><mrow><mi>d</mi></mrow><mrow><mn>17</mn></mrow></msup><mi>τ</mi><mo>)</mo></math></span> where <em>d</em> and <em>τ</em> bound the degree and the bitsize of the integer coefficients, respectively, of the defining polynomials of the curve and polylogarithmic factors are ignored. To the best of our knowledge, this improves upon the best currently known results at least by a factor of <span><math><msup><mrow><mi>d</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span>.</p></div>","PeriodicalId":50031,"journal":{"name":"Journal of Symbolic Computation","volume":"125 ","pages":"Article 102309"},"PeriodicalIF":0.7,"publicationDate":"2024-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139919633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Rational solutions to the first order difference equations in the bivariate difference field","authors":"Qing-Hu Hou , Yarong Wei","doi":"10.1016/j.jsc.2024.102308","DOIUrl":"https://doi.org/10.1016/j.jsc.2024.102308","url":null,"abstract":"<div><p>Inspired by Karr's algorithm, we consider the summations involving a sequence satisfying a recurrence of order two. The structure of such summations provides an algebraic framework for solving the difference equations of form <span><math><mi>a</mi><mi>σ</mi><mo>(</mo><mi>g</mi><mo>)</mo><mo>+</mo><mi>b</mi><mi>g</mi><mo>=</mo><mi>f</mi></math></span> in the bivariate difference field <span><math><mo>(</mo><mi>F</mi><mo>(</mo><mi>α</mi><mo>,</mo><mi>β</mi><mo>)</mo><mo>,</mo><mi>σ</mi><mo>)</mo></math></span>, where <span><math><mi>a</mi><mo>,</mo><mi>b</mi><mo>,</mo><mi>f</mi><mo>∈</mo><mi>F</mi><mo>(</mo><mi>α</mi><mo>,</mo><mi>β</mi><mo>)</mo><mo>∖</mo><mo>{</mo><mn>0</mn><mo>}</mo></math></span> are known binary functions of <em>α</em>, <em>β</em>, and <em>α</em>, <em>β</em> are two algebraically independent transcendental elements, <em>σ</em> is a transformation that satisfies <span><math><mi>σ</mi><mo>(</mo><mi>α</mi><mo>)</mo><mo>=</mo><mi>β</mi></math></span>, <span><math><mi>σ</mi><mo>(</mo><mi>β</mi><mo>)</mo><mo>=</mo><mi>u</mi><mi>α</mi><mo>+</mo><mi>v</mi><mi>β</mi></math></span>, where <span><math><mi>u</mi><mo>,</mo><mi>v</mi><mo>≠</mo><mn>0</mn><mo>∈</mo><mi>F</mi></math></span>. Based on it, we then describe algorithms for finding the universal denominator for those equations in the bivariate difference field under certain assumptions. This reduces the general problem of finding the rational solutions of such equations to the problem of finding the polynomial solutions of such equations.</p></div>","PeriodicalId":50031,"journal":{"name":"Journal of Symbolic Computation","volume":"124 ","pages":"Article 102308"},"PeriodicalIF":0.7,"publicationDate":"2024-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139901497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gemma De las Cuevas , Matt Hoogsteder Riera , Tim Netzer
{"title":"Tensor decompositions on simplicial complexes with invariance","authors":"Gemma De las Cuevas , Matt Hoogsteder Riera , Tim Netzer","doi":"10.1016/j.jsc.2024.102299","DOIUrl":"10.1016/j.jsc.2024.102299","url":null,"abstract":"<div><p><span>Tensors are ubiquitous in mathematics and the sciences, as they allow to store information in a concise way. Decompositions of tensors may give insights into their structure and complexity. In this work, we develop a new framework for decompositions of tensors, taking into account invariance, positivity and a geometric arrangement of their local spaces. We define an invariant decomposition with indices arranged on a simplicial complex which is explicitly invariant under a group action. We give a constructive proof that this decomposition exists for all invariant tensors, after possibly enriching the simplicial complex. We further define several decompositions certifying positivity, and prove similar existence results, as well as inequalities between the corresponding ranks. Our results generalize results from the theory of </span>tensor networks, used in the study of quantum many-body systems, for example.</p></div>","PeriodicalId":50031,"journal":{"name":"Journal of Symbolic Computation","volume":"124 ","pages":"Article 102299"},"PeriodicalIF":0.7,"publicationDate":"2024-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139497517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Computing the binomial part of a polynomial ideal","authors":"Martin Kreuzer, Florian Walsh","doi":"10.1016/j.jsc.2024.102298","DOIUrl":"10.1016/j.jsc.2024.102298","url":null,"abstract":"<div><p>Given an ideal <em>I</em> in a polynomial ring <span><math><mi>K</mi><mo>[</mo><msub><mrow><mi>x</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mo>…</mo><mo>,</mo><msub><mrow><mi>x</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>]</mo></math></span> over a field <em>K</em>, we present a complete algorithm to compute the binomial part of <em>I</em>, i.e., the subideal <span><math><mrow><mi>Bin</mi></mrow><mo>(</mo><mi>I</mi><mo>)</mo></math></span> of <em>I</em> generated by all monomials and binomials in <em>I</em>. This is achieved step-by-step. First we collect and extend several algorithms for computing exponent lattices in different kinds of fields. Then we generalize them to compute exponent lattices of units in 0-dimensional <em>K</em>-algebras, where we have to generalize the computation of the separable part of an algebra to non-perfect fields in characteristic <em>p</em>. Next we examine the computation of unit lattices in finitely generated <em>K</em>-algebras, as well as their associated characters and lattice ideals. This allows us to calculate <span><math><mrow><mi>Bin</mi></mrow><mo>(</mo><mi>I</mi><mo>)</mo></math></span> when <em>I</em> is saturated with respect to the indeterminates by reducing the task to the 0-dimensional case. Finally, we treat the computation of <span><math><mrow><mi>Bin</mi></mrow><mo>(</mo><mi>I</mi><mo>)</mo></math></span> for general ideals by computing their cellular decomposition and dealing with finitely many special ideals called <span><math><mo>(</mo><mi>s</mi><mo>,</mo><mi>t</mi><mo>)</mo></math></span>-binomial parts. All algorithms have been implemented in <span>SageMath</span>.</p></div>","PeriodicalId":50031,"journal":{"name":"Journal of Symbolic Computation","volume":"124 ","pages":"Article 102298"},"PeriodicalIF":0.7,"publicationDate":"2024-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0747717124000026/pdfft?md5=bc32bb62dcb12f7f2c1d113994ec49bf&pid=1-s2.0-S0747717124000026-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139462707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alberto Alzati, Daniele Di Tullio, Manoj Gyawali, Alfonso Tortora
{"title":"A post-quantum key exchange protocol from the intersection of conics","authors":"Alberto Alzati, Daniele Di Tullio, Manoj Gyawali, Alfonso Tortora","doi":"10.1016/j.jsc.2024.102297","DOIUrl":"https://doi.org/10.1016/j.jsc.2024.102297","url":null,"abstract":"<p>In this paper we present a key exchange protocol in which Alice and Bob have secret keys given by two conics embedded in a large ambient space by means of the Veronese embedding and public keys given by hyperplanes containing the embedded curves. Both of them construct some common invariants given by the intersection of two conics.</p>","PeriodicalId":50031,"journal":{"name":"Journal of Symbolic Computation","volume":"7 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2024-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139102670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Theta nullvalues of supersingular Abelian varieties","authors":"Andreas Pieper","doi":"10.1016/j.jsc.2023.102296","DOIUrl":"10.1016/j.jsc.2023.102296","url":null,"abstract":"<div><p>Let <em>η</em><span> be a polarization with connected kernel on a superspecial abelian variety </span><span><math><msup><mrow><mi>E</mi></mrow><mrow><mi>g</mi></mrow></msup></math></span>. We give a sufficient criterion which allows the computation of the theta nullvalues of any quotient of <span><math><msup><mrow><mi>E</mi></mrow><mrow><mi>g</mi></mrow></msup></math></span> by a maximal isotropic subgroup scheme of <span><math><mi>ker</mi><mo></mo><mo>(</mo><mi>η</mi><mo>)</mo></math></span> effectively.</p><p>This criterion is satisfied in many situations studied by <span>Li and Oort (1998)</span>. We used our method to implement an algorithm that computes supersingular curves of genus 3.</p></div>","PeriodicalId":50031,"journal":{"name":"Journal of Symbolic Computation","volume":"123 ","pages":"Article 102296"},"PeriodicalIF":0.7,"publicationDate":"2023-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139065849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Clemens Heuberger , Daniel Krenn , Gabriel F. Lipnik
{"title":"A note on the relation between recognisable series and regular sequences, and their minimal linear representations","authors":"Clemens Heuberger , Daniel Krenn , Gabriel F. Lipnik","doi":"10.1016/j.jsc.2023.102295","DOIUrl":"10.1016/j.jsc.2023.102295","url":null,"abstract":"<div><p>In this note, we precisely elaborate the connection between recognisable series (in the sense of Berstel and Reutenauer) and <em>q</em>-regular sequences (in the sense of Allouche and Shallit) via their linear representations. In particular, we show that the minimisation algorithm for recognisable series can also be used to minimise linear representations of <em>q</em>-regular sequences.</p></div>","PeriodicalId":50031,"journal":{"name":"Journal of Symbolic Computation","volume":"123 ","pages":"Article 102295"},"PeriodicalIF":0.7,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0747717123001098/pdfft?md5=492907babc8de19f0ee8ae11896722d4&pid=1-s2.0-S0747717123001098-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139065963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Axioms for a theory of signature bases","authors":"Pierre Lairez","doi":"10.1016/j.jsc.2023.102275","DOIUrl":"10.1016/j.jsc.2023.102275","url":null,"abstract":"<div><p><span>Twenty years after the discovery of the F5 algorithm, Gröbner bases with signatures are still challenging to understand and to adapt to different settings. This contrasts with Buchberger's algorithm, which we can bend in many directions keeping correctness and termination obvious. I propose an axiomatic approach to Gröbner bases with signatures with the purpose of uncoupling the theory and the algorithms, giving general results applicable in many different settings (e.g. Gröbner for </span>submodules, F4-style reduction, noncommutative rings, non-Noetherian settings, etc.), and extending the reach of signature algorithms.</p></div>","PeriodicalId":50031,"journal":{"name":"Journal of Symbolic Computation","volume":"123 ","pages":"Article 102275"},"PeriodicalIF":0.7,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138742217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Computing primitive idempotents in finite commutative rings and applications","authors":"Mugurel Barcau , Vicenţiu Paşol","doi":"10.1016/j.jsc.2023.102294","DOIUrl":"10.1016/j.jsc.2023.102294","url":null,"abstract":"<div><p><span>In this paper, we compute an algebraic decomposition of black-box rings in the generic ring model. More precisely, we explicitly decompose a black-box ring as a direct product of a nilpotent black-box ring and unital local black-box rings, by computing all its primitive idempotents. The algorithm presented in this paper uses quantum subroutines for the computation of the </span><em>p</em>-power parts of a black-box ring and then classical algorithms for the computation of the corresponding primitive idempotents. As a by-product, we get that the reduction of a black-box ring is also a black-box ring. The first application of this decomposition is an extension of the work of <span>Maurer and Raub (2007)</span> on representation problem in black-box finite fields to the case of reduced <em>p</em>-power black-box rings. Another important application is an <span><math><msup><mrow><mtext>IND-CCA</mtext></mrow><mrow><mn>1</mn></mrow></msup></math></span><span> attack for any ring homomorphic encryption scheme<span> in the generic ring model. Moreover, when the plaintext space is a finite reduced black-box ring, we present a plaintext-recovery attack based on representation problem in black-box prime fields. In particular, if the ciphertext space has smooth characteristic, the plaintext-recovery attack is effectively computable in the generic ring model.</span></span></p></div>","PeriodicalId":50031,"journal":{"name":"Journal of Symbolic Computation","volume":"123 ","pages":"Article 102294"},"PeriodicalIF":0.7,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138688298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}