Pub Date : 2023-07-13DOI: 10.1142/s2010324723500224
M. Mebrek, B. Medjahed, M. Zemouli, Benabdellah Benyamina, Mohamed Berber, Djillali Benziadi, S. Amrani
{"title":"Investigation of structural, magnetic, and elastic properties of a new Full- Heusler alloy Ir2FeAl","authors":"M. Mebrek, B. Medjahed, M. Zemouli, Benabdellah Benyamina, Mohamed Berber, Djillali Benziadi, S. Amrani","doi":"10.1142/s2010324723500224","DOIUrl":"https://doi.org/10.1142/s2010324723500224","url":null,"abstract":"","PeriodicalId":54319,"journal":{"name":"Spin","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42783095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-13DOI: 10.1142/s2010324723500212
E. Albayrak
{"title":"The XZ model in the Mean-Field Approximation with Exponential Pauli Spin Matrices","authors":"E. Albayrak","doi":"10.1142/s2010324723500212","DOIUrl":"https://doi.org/10.1142/s2010324723500212","url":null,"abstract":"","PeriodicalId":54319,"journal":{"name":"Spin","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48109243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-07DOI: 10.1142/s2010324723500200
Shizhu Qiao
{"title":"Rotational symmetry breaking enhanced frequency comb of NiFe vortex in a square disk","authors":"Shizhu Qiao","doi":"10.1142/s2010324723500200","DOIUrl":"https://doi.org/10.1142/s2010324723500200","url":null,"abstract":"","PeriodicalId":54319,"journal":{"name":"Spin","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47081624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-07DOI: 10.1142/s2010324723300013
Guanru Feng, Dawei Lu, Jun Li, T. Xin, B. Zeng
{"title":"Quantum computing principles and applications","authors":"Guanru Feng, Dawei Lu, Jun Li, T. Xin, B. Zeng","doi":"10.1142/s2010324723300013","DOIUrl":"https://doi.org/10.1142/s2010324723300013","url":null,"abstract":"","PeriodicalId":54319,"journal":{"name":"Spin","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44621719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-06DOI: 10.48550/arXiv.2307.02774
Elena Grigorescu, Nithish Kumar, Young-San Lin
In the pairwise weighted spanner problem, the input consists of an $n$-vertex-directed graph, where each edge is assigned a cost and a length. Given $k$ vertex pairs and a distance constraint for each pair, the goal is to find a minimum-cost subgraph in which the distance constraints are satisfied. This formulation captures many well-studied connectivity problems, including spanners, distance preservers, and Steiner forests. In the offline setting, we show: 1. An $tilde{O}(n^{4/5 + epsilon})$-approximation algorithm for pairwise weighted spanners. When the edges have unit costs and lengths, the best previous algorithm gives an $tilde{O}(n^{3/5 + epsilon})$-approximation, due to Chlamt'av{c}, Dinitz, Kortsarz, and Laekhanukit (TALG, 2020). 2. An $tilde{O}(n^{1/2+epsilon})$-approximation algorithm for all-pair weighted distance preservers. When the edges have unit costs and arbitrary lengths, the best previous algorithm gives an $tilde{O}(n^{1/2})$-approximation for all-pair spanners, due to Berman, Bhattacharyya, Makarychev, Raskhodnikova, and Yaroslavtsev (Information and Computation, 2013). In the online setting, we show: 1. An $tilde{O}(k^{1/2 + epsilon})$-competitive algorithm for pairwise weighted spanners. The state-of-the-art results are $tilde{O}(n^{4/5})$-competitive when edges have unit costs and arbitrary lengths, and $min{tilde{O}(k^{1/2 + epsilon}), tilde{O}(n^{2/3 + epsilon})}$-competitive when edges have unit costs and lengths, due to Grigorescu, Lin, and Quanrud (APPROX, 2021). 2. An $tilde{O}(k^{epsilon})$-competitive algorithm for single-source weighted spanners. Without distance constraints, this problem is equivalent to the directed Steiner tree problem. The best previous algorithm for online directed Steiner trees is $tilde{O}(k^{epsilon})$-competitive, due to Chakrabarty, Ene, Krishnaswamy, and Panigrahi (SICOMP, 2018).
{"title":"Approximation Algorithms for Directed Weighted Spanners","authors":"Elena Grigorescu, Nithish Kumar, Young-San Lin","doi":"10.48550/arXiv.2307.02774","DOIUrl":"https://doi.org/10.48550/arXiv.2307.02774","url":null,"abstract":"In the pairwise weighted spanner problem, the input consists of an $n$-vertex-directed graph, where each edge is assigned a cost and a length. Given $k$ vertex pairs and a distance constraint for each pair, the goal is to find a minimum-cost subgraph in which the distance constraints are satisfied. This formulation captures many well-studied connectivity problems, including spanners, distance preservers, and Steiner forests. In the offline setting, we show: 1. An $tilde{O}(n^{4/5 + epsilon})$-approximation algorithm for pairwise weighted spanners. When the edges have unit costs and lengths, the best previous algorithm gives an $tilde{O}(n^{3/5 + epsilon})$-approximation, due to Chlamt'av{c}, Dinitz, Kortsarz, and Laekhanukit (TALG, 2020). 2. An $tilde{O}(n^{1/2+epsilon})$-approximation algorithm for all-pair weighted distance preservers. When the edges have unit costs and arbitrary lengths, the best previous algorithm gives an $tilde{O}(n^{1/2})$-approximation for all-pair spanners, due to Berman, Bhattacharyya, Makarychev, Raskhodnikova, and Yaroslavtsev (Information and Computation, 2013). In the online setting, we show: 1. An $tilde{O}(k^{1/2 + epsilon})$-competitive algorithm for pairwise weighted spanners. The state-of-the-art results are $tilde{O}(n^{4/5})$-competitive when edges have unit costs and arbitrary lengths, and $min{tilde{O}(k^{1/2 + epsilon}), tilde{O}(n^{2/3 + epsilon})}$-competitive when edges have unit costs and lengths, due to Grigorescu, Lin, and Quanrud (APPROX, 2021). 2. An $tilde{O}(k^{epsilon})$-competitive algorithm for single-source weighted spanners. Without distance constraints, this problem is equivalent to the directed Steiner tree problem. The best previous algorithm for online directed Steiner trees is $tilde{O}(k^{epsilon})$-competitive, due to Chakrabarty, Ene, Krishnaswamy, and Panigrahi (SICOMP, 2018).","PeriodicalId":54319,"journal":{"name":"Spin","volume":"463 1","pages":"8:1-8:23"},"PeriodicalIF":1.8,"publicationDate":"2023-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81738430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-05DOI: 10.48550/arXiv.2307.02205
Anita Dürr, Nicolas El Maalouly, Lasse Wulf
In 1982 Papadimitriou and Yannakakis introduced the Exact Matching problem, in which given a red and blue edge-colored graph $G$ and an integer $k$ one has to decide whether there exists a perfect matching in $G$ with exactly $k$ red edges. Even though a randomized polynomial-time algorithm for this problem was quickly found a few years later, it is still unknown today whether a deterministic polynomial-time algorithm exists. This makes the Exact Matching problem an important candidate to test the RP=P hypothesis. In this paper we focus on approximating Exact Matching. While there exists a simple algorithm that computes in deterministic polynomial-time an almost perfect matching with exactly $k$ red edges, not a lot of work focuses on computing perfect matchings with almost $k$ red edges. In fact such an algorithm for bipartite graphs running in deterministic polynomial-time was published only recently (STACS'23). It outputs a perfect matching with $k'$ red edges with the guarantee that $0.5k leq k' leq 1.5k$. In the present paper we aim at approximating the number of red edges without exceeding the limit of $k$ red edges. We construct a deterministic polynomial-time algorithm, which on bipartite graphs computes a perfect matching with $k'$ red edges such that $k/3 leq k' leq k$.
1982年，Papadimitriou和Yannakakis引入了精确匹配问题，在这个问题中，给定一个红色和蓝色边的图$G$和一个整数$k$，人们必须决定$G$中是否存在一个与恰好$k$条红边完美匹配的图。尽管在几年后很快就找到了解决这个问题的随机多项式时间算法，但今天仍然不知道是否存在确定性多项式时间算法。这使得精确匹配问题成为检验RP=P假设的重要候选者。本文主要研究近似精确匹配。虽然存在一种简单的算法，可以在确定性多项式时间内计算出与$k$红边精确匹配的几乎完美匹配，但并没有太多的工作集中在计算几乎$k$红边的完美匹配上。事实上，这种在确定性多项式时间内运行的二部图的算法直到最近才发表(STACS'23)。它输出与$k'$红边的完美匹配，并保证$0.5k leq k' leq 1.5k$。在本文中，我们的目标是在不超过$k$红边限制的情况下逼近红边的数目。我们构造了一个确定性多项式时间算法，该算法在二部图上计算与$k'$红边的完美匹配，使得$k/3 leq k' leq k$。
{"title":"An Approximation Algorithm for the Exact Matching Problem in Bipartite Graphs","authors":"Anita Dürr, Nicolas El Maalouly, Lasse Wulf","doi":"10.48550/arXiv.2307.02205","DOIUrl":"https://doi.org/10.48550/arXiv.2307.02205","url":null,"abstract":"In 1982 Papadimitriou and Yannakakis introduced the Exact Matching problem, in which given a red and blue edge-colored graph $G$ and an integer $k$ one has to decide whether there exists a perfect matching in $G$ with exactly $k$ red edges. Even though a randomized polynomial-time algorithm for this problem was quickly found a few years later, it is still unknown today whether a deterministic polynomial-time algorithm exists. This makes the Exact Matching problem an important candidate to test the RP=P hypothesis. In this paper we focus on approximating Exact Matching. While there exists a simple algorithm that computes in deterministic polynomial-time an almost perfect matching with exactly $k$ red edges, not a lot of work focuses on computing perfect matchings with almost $k$ red edges. In fact such an algorithm for bipartite graphs running in deterministic polynomial-time was published only recently (STACS'23). It outputs a perfect matching with $k'$ red edges with the guarantee that $0.5k leq k' leq 1.5k$. In the present paper we aim at approximating the number of red edges without exceeding the limit of $k$ red edges. We construct a deterministic polynomial-time algorithm, which on bipartite graphs computes a perfect matching with $k'$ red edges such that $k/3 leq k' leq k$.","PeriodicalId":54319,"journal":{"name":"Spin","volume":"92 1","pages":"18:1-18:21"},"PeriodicalIF":1.8,"publicationDate":"2023-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74646277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-02DOI: 10.48550/arXiv.2307.00683
Antonio Blanca, Xusheng Zhang
We consider spin systems on general $n$-vertex graphs of unbounded degree and explore the effects of spectral independence on the rate of convergence to equilibrium of global Markov chains. Spectral independence is a novel way of quantifying the decay of correlations in spin system models, which has significantly advanced the study of Markov chains for spin systems. We prove that whenever spectral independence holds, the popular Swendsen--Wang dynamics for the $q$-state ferromagnetic Potts model on graphs of maximum degree $Delta$, where $Delta$ is allowed to grow with $n$, converges in $O((Delta log n)^c)$ steps where $c>0$ is a constant independent of $Delta$ and $n$. We also show a similar mixing time bound for the block dynamics of general spin systems, again assuming that spectral independence holds. Finally, for monotone spin systems such as the Ising model and the hardcore model on bipartite graphs, we show that spectral independence implies that the mixing time of the systematic scan dynamics is $O(Delta^c log n)$ for a constant $c>0$ independent of $Delta$ and $n$. Systematic scan dynamics are widely popular but are notoriously difficult to analyze. Our result implies optimal $O(log n)$ mixing time bounds for any systematic scan dynamics of the ferromagnetic Ising model on general graphs up to the tree uniqueness threshold. Our main technical contribution is an improved factorization of the entropy functional: this is the common starting point for all our proofs. Specifically, we establish the so-called $k$-partite factorization of entropy with a constant that depends polynomially on the maximum degree of the graph.
{"title":"Rapid mixing of global Markov chains via spectral independence: the unbounded degree case","authors":"Antonio Blanca, Xusheng Zhang","doi":"10.48550/arXiv.2307.00683","DOIUrl":"https://doi.org/10.48550/arXiv.2307.00683","url":null,"abstract":"We consider spin systems on general $n$-vertex graphs of unbounded degree and explore the effects of spectral independence on the rate of convergence to equilibrium of global Markov chains. Spectral independence is a novel way of quantifying the decay of correlations in spin system models, which has significantly advanced the study of Markov chains for spin systems. We prove that whenever spectral independence holds, the popular Swendsen--Wang dynamics for the $q$-state ferromagnetic Potts model on graphs of maximum degree $Delta$, where $Delta$ is allowed to grow with $n$, converges in $O((Delta log n)^c)$ steps where $c>0$ is a constant independent of $Delta$ and $n$. We also show a similar mixing time bound for the block dynamics of general spin systems, again assuming that spectral independence holds. Finally, for monotone spin systems such as the Ising model and the hardcore model on bipartite graphs, we show that spectral independence implies that the mixing time of the systematic scan dynamics is $O(Delta^c log n)$ for a constant $c>0$ independent of $Delta$ and $n$. Systematic scan dynamics are widely popular but are notoriously difficult to analyze. Our result implies optimal $O(log n)$ mixing time bounds for any systematic scan dynamics of the ferromagnetic Ising model on general graphs up to the tree uniqueness threshold. Our main technical contribution is an improved factorization of the entropy functional: this is the common starting point for all our proofs. Specifically, we establish the so-called $k$-partite factorization of entropy with a constant that depends polynomially on the maximum degree of the graph.","PeriodicalId":54319,"journal":{"name":"Spin","volume":"20 1","pages":"53:1-53:19"},"PeriodicalIF":1.8,"publicationDate":"2023-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82400589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-15DOI: 10.1142/s2010324723500182
Morteza Adelkhani, M. Aminian
{"title":"Low Power and Fully Non-Volatile Full-Adder based on STT-SHE-MRAM","authors":"Morteza Adelkhani, M. Aminian","doi":"10.1142/s2010324723500182","DOIUrl":"https://doi.org/10.1142/s2010324723500182","url":null,"abstract":"","PeriodicalId":54319,"journal":{"name":"Spin","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41919935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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