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Ramsey achievement games on graphs : algorithms and bounds Ramsey成就游戏：算法和界限
IF 0.5 4区 计算机科学
Acta Informatica Pub Date : 2026-02-09 DOI: 10.1007/s00236-025-00516-9
Xiumin Wang, Zhong Huang, Xiangqian Zhou, Ralf Klasing, Yaping Mao
{"title":"Ramsey achievement games on graphs : algorithms and bounds","authors":"Xiumin Wang,&nbsp;Zhong Huang,&nbsp;Xiangqian Zhou,&nbsp;Ralf Klasing,&nbsp;Yaping Mao","doi":"10.1007/s00236-025-00516-9","DOIUrl":"10.1007/s00236-025-00516-9","url":null,"abstract":"<div><p>In 1982, Harary introduced the concept of Ramsey achievement game on graphs. Given a graph <i>F</i> with no isolated vertices, consider the following game played on the complete graph <span>(K_n)</span> by two players Alice and Bob. First, Alice colors one of the edges of <span>(K_n)</span> blue, then Bob colors a different edge red, and so on. The first player who can complete the formation of <i>F</i> in his color is the winner. The minimum <i>n</i> for which Alice has a winning strategy is the achievement number of <i>F</i>, denoted by <i>a</i>(<i>F</i>). If we replace <span>(K_n)</span> in the game by the complete bipartite graph <span>(K_{n,n})</span>, we get the bipartite achievement number, denoted by <span>(operatorname {ba}(F))</span>. In this paper, we correct <span>(operatorname {ba}(mK_2)=m+1)</span> to <i>m</i> and disprove <span>(operatorname {ba}(K_{1,m})=2m-2)</span> from Erickson and Harary (1983). We also find the exact values or upper and lower bounds of bipartite achievement numbers on matchings, stars, and double stars.</p></div>","PeriodicalId":7189,"journal":{"name":"Acta Informatica","volume":"63 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2026-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147338295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Opacity complexity of automatic sequences: the general case 自动序列的不透明度复杂度：一般情况
IF 0.5 4区 计算机科学
Acta Informatica Pub Date : 2026-02-09 DOI: 10.1007/s00236-026-00521-6
Jean-Paul Allouche, Jia-Yan Yao
{"title":"Opacity complexity of automatic sequences: the general case","authors":"Jean-Paul Allouche,&nbsp;Jia-Yan Yao","doi":"10.1007/s00236-026-00521-6","DOIUrl":"10.1007/s00236-026-00521-6","url":null,"abstract":"<div><p>In this work we introduce a new notion called opacity complexity to measure the complexity of automatic sequences. We study basic properties of this notion, and exhibit an algorithm to compute it. As applications, we compute the opacity complexity of some well-known automatic sequences, including in particular constant sequences, purely periodic sequences, the Thue-Morse sequence, the period-doubling sequence, the Golay-Shapiro(-Rudin) sequence, the paperfolding sequence, the Baum-Sweet sequence, the Tower of Hanoi sequence, and so on.</p></div>","PeriodicalId":7189,"journal":{"name":"Acta Informatica","volume":"63 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2026-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147338294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Distance labeling for families of cycles 循环族的距离标记
IF 0.5 4区 计算机科学
Acta Informatica Pub Date : 2026-01-31 DOI: 10.1007/s00236-025-00517-8
Arseny M. Shur, Mikhail Rubinchik
{"title":"Distance labeling for families of cycles","authors":"Arseny M. Shur,&nbsp;Mikhail Rubinchik","doi":"10.1007/s00236-025-00517-8","DOIUrl":"10.1007/s00236-025-00517-8","url":null,"abstract":"<div><p>For an arbitrary finite family of graphs, the distance labeling problem asks to assign labels to all nodes of every graph in the family in a way that allows one to recover the distance between any two nodes of any graph from their labels. The main goal is to minimize the number of unique labels used. We study this problem for the families <span>(mathcal {C}_n)</span> consisting of cycles of all lengths between 3 and <i>n</i>. We observe that the exact solution for directed cycles is straightforward and focus on the undirected case. We design a labeling scheme requiring <span>(frac{nsqrt{n}}{sqrt{6}}+O(n))</span> labels, which is almost twice less than is required by the earlier known scheme. Using the computer search, we find an optimal labeling for each <span>(nle 17)</span>, showing that our scheme gives the results that are very close to the optimum.</p></div>","PeriodicalId":7189,"journal":{"name":"Acta Informatica","volume":"63 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2026-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146083093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Internal contextual grammars with resources restricted and structure limited selection 资源受限、结构选择受限的内部上下文语法
IF 0.5 4区 计算机科学
Acta Informatica Pub Date : 2026-01-31 DOI: 10.1007/s00236-025-00520-z
Bianca Truthe
{"title":"Internal contextual grammars with resources restricted and structure limited selection","authors":"Bianca Truthe","doi":"10.1007/s00236-025-00520-z","DOIUrl":"10.1007/s00236-025-00520-z","url":null,"abstract":"<div><p>In this paper, we continue the research on the power of contextual grammars with selection languages from subfamilies of the family of regular languages. In the past, two independent hierarchies have been obtained for external and internal contextual grammars, one based on selection languages defined by structural properties (finite, monoidal, nilpotent, combinational, definite, ordered, non-counting, power-separating, suffix-closed, commutative, circular, or union-free languages), the other one based on selection languages defined by resources (number of non-terminal symbols, production rules, or states needed for generating or accepting them). In a previous paper, the language families of these hierarchies for external contextual grammars were compared and the hierarchies merged. In the present paper, we compare the language families of these hierarchies for internal contextual grammars and merge these hierarchies.</p></div>","PeriodicalId":7189,"journal":{"name":"Acta Informatica","volume":"63 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2026-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00236-025-00520-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146083094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Sweeping permutation automata 清扫排列自动机
IF 0.5 4区 计算机科学
Acta Informatica Pub Date : 2026-01-31 DOI: 10.1007/s00236-025-00519-6
Maria Radionova, Alexander Okhotin
{"title":"Sweeping permutation automata","authors":"Maria Radionova,&nbsp;Alexander Okhotin","doi":"10.1007/s00236-025-00519-6","DOIUrl":"10.1007/s00236-025-00519-6","url":null,"abstract":"<div><p>This paper introduces sweeping permutation automata, which move over an input string in alternating left-to-right and right-to-left sweeps and have a bijective transition function. It is proved that these automata recognize the same family of languages as the classical one-way permutation automata (Thierrin, “Permutation automata”, <i>Mathematical Systems Theory</i>, 1968). The proof is constructive: an <i>n</i>-state two-way permutation automaton is transformed to a one-way permutation automaton with at most <span>(F(n)=max _{k+ell =n, m leqslant ell } k cdot { ell atopwithdelims ()m} cdot {k - 1 atopwithdelims ()ell - m} cdot (ell - m)!)</span> states (here the maximum is over all partitions of <i>n</i> into <i>k</i> states with transitions to the right and <span>(ell)</span> states with transitions to the left, where <i>m</i> states have no transitions on the left end-marker). This number of states is proved to be necessary in the worst case, and its growth rate is estimated as <span>(F(n) = n^{frac{n}{2} - frac{1 + ln 2}{2}frac{n}{ln n}(1 + o(1))})</span>.</p></div>","PeriodicalId":7189,"journal":{"name":"Acta Informatica","volume":"63 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2026-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146083195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
On the hardness and approximation of the densest k-subgraph problem in parameterized metric graphs 参数化度量图中最密集k子图问题的硬度和逼近性
IF 0.5 4区 计算机科学
Acta Informatica Pub Date : 2026-01-31 DOI: 10.1007/s00236-025-00518-7
Shih-Chia Chang, Li-Hsuan Chen, Sun-Yuan Hsieh, Ling-Ju Hung, Shih-Shun Kao, Ralf Klasing
{"title":"On the hardness and approximation of the densest k-subgraph problem in parameterized metric graphs","authors":"Shih-Chia Chang,&nbsp;Li-Hsuan Chen,&nbsp;Sun-Yuan Hsieh,&nbsp;Ling-Ju Hung,&nbsp;Shih-Shun Kao,&nbsp;Ralf Klasing","doi":"10.1007/s00236-025-00518-7","DOIUrl":"10.1007/s00236-025-00518-7","url":null,"abstract":"<div><p>A complete weighted graph <span>(G= (V, E, w))</span> is called <span>(Delta _{beta })</span>-metric, for some <span>(beta ge 1/2)</span>, if <i>G</i> satisfies the <span>(beta)</span>-triangle inequality, <i>i.e.,</i> <span>(w(u,v) le beta cdot (w(u,x) + w(x,v)))</span> for all vertices <span>(u,v,xin V)</span>. Given a <span>(Delta _{beta })</span>-metric graph <span>(G=(V, E, w))</span>, the <span>(Delta _{beta })</span><span>-Weighted Densest</span> <i>k</i><span>-Subgraph</span> (<span>(Delta _{beta })</span>-WD<i>k</i>S) problem is to find an induced subgraph <i>G</i>[<i>C</i>] with exactly <i>k</i> vertices such that the total edge weight of <i>G</i>[<i>C</i>] is maximized. For <span>(beta = 1)</span>, this problem, <span>(Delta)</span>-WD<i>k</i>S, is known NP-hard and admits a <span>(frac{1}{2})</span>-approximation algorithm. In this paper, we show the NP-hardness and the inapproximability of the <span>(Delta _{beta })</span>-WD<i>k</i>S problem for any <span>(beta&gt; 1/2)</span>. We prove that <span>(Delta _{beta })</span>-WD<i>k</i>S can be approximated to within a factor <span>((frac{1}{2beta }+frac{2beta -1}{2beta cdot (2k-3)}))</span> for any <span>(beta&gt; frac{1}{2})</span> and show that the analysis of the approximation ratio is asymptotically tight. Additionally, we describe a method to adapt any <span>(alpha)</span>-approximation algorithm for <span>(Delta)</span>-WD<i>k</i>S to obtain a <span>(delta _{alpha ,beta })</span>-approximation algorithm for <span>(Delta _{beta })</span>-WD<i>k</i>S with <span>(delta _{alpha ,beta }&gt; alpha)</span> for every <span>(beta &lt;1)</span>. This allows for improved approximations for <span>(Delta _{beta })</span>-WD<i>k</i>S instances, offering potential enhancements to existing algorithms for this problem.</p></div>","PeriodicalId":7189,"journal":{"name":"Acta Informatica","volume":"63 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2026-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146083057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Message recovery attack in NTRU through VFK lattices 通过VFK格的NTRU报文恢复攻击
IF 0.5 4区 计算机科学
Acta Informatica Pub Date : 2026-01-08 DOI: 10.1007/s00236-025-00512-z
Eirini D. Poimenidou, Marios Adamoudis, K. A. Draziotis, Kostas Tsichlas
{"title":"Message recovery attack in NTRU through VFK lattices","authors":"Eirini D. Poimenidou,&nbsp;Marios Adamoudis,&nbsp;K. A. Draziotis,&nbsp;Kostas Tsichlas","doi":"10.1007/s00236-025-00512-z","DOIUrl":"10.1007/s00236-025-00512-z","url":null,"abstract":"<div><p>In the present paper, we introduce a message recovery attack applicable to NTRU cryptosystem. Our methodology uses a reduction from the NTRU-lattice to a Voronoi First Kind (VFK) lattice, enabling the use of a polynomial Closest Vector Problem (CVP) exact algorithm, which is vital for successful message recovery. This approach assumes knowledge of the Most Significant Bit of the coefficients of a polynomial that is a multiple of the nonce. Finally, extensive experimental results for the NTRU-HPS variants submitted to NIST are presented. The findings highlight the need to properly protect NTRU schemes against potential leakage.</p></div>","PeriodicalId":7189,"journal":{"name":"Acta Informatica","volume":"63 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145908994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Hypernode automata Hypernode自动机
IF 0.5 4区 计算机科学
Acta Informatica Pub Date : 2025-12-09 DOI: 10.1007/s00236-025-00509-8
Ezio Bartocci, Marek Chalupa, Thomas A. Henzinger, Dejan Nickovic, Ana Oliveira da Costa
{"title":"Hypernode automata","authors":"Ezio Bartocci,&nbsp;Marek Chalupa,&nbsp;Thomas A. Henzinger,&nbsp;Dejan Nickovic,&nbsp;Ana Oliveira da Costa","doi":"10.1007/s00236-025-00509-8","DOIUrl":"10.1007/s00236-025-00509-8","url":null,"abstract":"<div><p>In this work, we present <i>hypernode automata</i> as a specification formalism for hyperproperties of systems whose executions may be misaligned among themselves, such as concurrent systems. These automata consist of nodes labeled with <i>hypernode logic</i> formulas and transitions marked with synchronizing actions. Hypernode logic formulas establish relations between sequences of variable values among different system executions. This logic enables both synchronous and asynchronous analysis of traces. In its asynchronous view on execution traces, hypernode formulas establish relations on the order of value changes for each variable without correlating their timing. In both views, the analysis of different execution traces is synchronized through the transitions of hypernode automata. By combining logic’s declarative nature with automata’s procedural power, hypernode automata seamlessly integrate asynchronicity requirements at the node level with synchronicity between node transitions. We show that the model-checking problem for hypernode automata is decidable for specifications where each node specifies either a synchronous or an asynchronous requirement for the system’s executions, but not both.</p></div>","PeriodicalId":7189,"journal":{"name":"Acta Informatica","volume":"62 4","pages":""},"PeriodicalIF":0.5,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00236-025-00509-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145729622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Editorial 2025: Going Beyond 40 社论2025：超越40岁
IF 0.5 4区 计算机科学
Acta Informatica Pub Date : 2025-12-08 DOI: 10.1007/s00236-025-00513-y
Henning Fernau
{"title":"Editorial 2025: Going Beyond 40","authors":"Henning Fernau","doi":"10.1007/s00236-025-00513-y","DOIUrl":"10.1007/s00236-025-00513-y","url":null,"abstract":"","PeriodicalId":7189,"journal":{"name":"Acta Informatica","volume":"62 4","pages":""},"PeriodicalIF":0.5,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145730035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
An efficient alternative strategy for finding prices in envy-free perfect matchings 在没有嫉妒的完美匹配中寻找价格的有效替代策略
IF 0.5 4区 计算机科学
Acta Informatica Pub Date : 2025-11-07 DOI: 10.1007/s00236-025-00511-0
Marcos Salvatierra, Juan G. Colonna, Mario Salvatierra, Alcides de C. Amorim Neto
{"title":"An efficient alternative strategy for finding prices in envy-free perfect matchings","authors":"Marcos Salvatierra,&nbsp;Juan G. Colonna,&nbsp;Mario Salvatierra,&nbsp;Alcides de C. Amorim Neto","doi":"10.1007/s00236-025-00511-0","DOIUrl":"10.1007/s00236-025-00511-0","url":null,"abstract":"<div><p>We present a method for finding envy-free prices in a combinatorial auction where the consumers’ number <i>n</i> coincides with that of distinct items for sale, each consumer can buy one single item and each item has only one unit available. This is a particular case of the <i>unit-demand envy-free pricing problem</i>, and was recently revisited by Arbib et al. (Discr Appl Math 261:22–27, 2019, https://doi.org/10.1016/j.dam.2018.03.034). These authors proved that using a Fibonacci heap for solving the maximum weight perfect matching and the Bellman-Ford algorithm for getting the envy-free prices, the overall time complexity for solving the problem is <span>(O(n^3))</span>. We propose a method based on dynamic programming design strategy that seeks the optimal envy-free prices by increasing the consumers’ utilities, which has the same cubic complexity time as the aforementioned approach, but whose theoretical and empirical results indicate that our method performs faster than the shortest paths strategy, obtaining an average time reduction in determining optimal envy-free prices of approximately 48%.</p></div>","PeriodicalId":7189,"journal":{"name":"Acta Informatica","volume":"62 4","pages":""},"PeriodicalIF":0.5,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145456228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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