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Intan Muchtadi-Alamsyah

Publications and source records attributed to Intan Muchtadi-Alamsyah.

9 recordsLinked to original sources
arXiv2021

Graph Sampling Approach for Reducing Computational Complexity of Large-Scale Social Network

Online social network services provide a platform for human social interactions. Nowadays, many kinds of online interactions generate large-scale social network data. Network analysis helps to mine knowledge and pattern from the relationship between actors inside the network. This approach is important to support predictions and the decision-making process in many real-world applications. The social network analysis methodology, which borrows approaches from graph theory provides several metrics that enabled us to measure specific properties of the networks. Some of the metrics calculations were built with no scalability in minds, thus it is computationally expensive. In this paper, we propose a graph sampling approach to reduce social network size, thus reducing computation operations. The performance comparison between natural graph sampling strategies using edge random sampling, node random sampling, and random walks are presented on each selected graph property. We found that the performance of graph sampling strategies depends on graph properties measured.

cs.SI↗
arXiv2019

Different exact structures on the monomorphism categories

Let $\mathcal{X}$ be a resolving and contravariantly finite subcategory of $\rm{mod}\mbox{-}Λ$, the category of finitely generated right $Λ$-modules. We associate to $\mathcal{X}$ the subcategory $\mathcal{S}_{\mathcal{X}}(Λ)$ of the morphism category $\rm{H}(Λ)$ consisting of all monomorphisms $(A\stackrel{f}\rightarrow B)$ with $A, B$ and $\rm{Cok} \ f$ in $\mathcal{\mathcal{X}}$. Since $\mathcal{S}_{\mathcal{X}}(Λ)$ is closed under extensions then it inherits naturally an exact structure from $\rm{H}(Λ)$. We will define two other different exact structures else than the canonical one on $\mathcal{S}_{\mathcal{X}}(Λ)$, and the indecomposable projective (resp. injective) objects in the corresponding exact categories completely classified. Enhancing $\mathcal{S}_{\mathcal{X}}(Λ)$ with the new exact structure provides a framework to construct a triangle functor. Let $\rm{mod}\mbox{-}\underline{\mathcal{X}}$ denote the category of finitely presented functors over the stable category $\underline{\mathcal{X}}$. We then use the triangle functor to show a triangle equivalence between the bounded derived category $\mathbb{D}^{\rm{b}}(\rm{mod}\mbox{-}\underline{\mathcal{X}})$ and a Verdier quotient of the bounded derived category of the associated exact category on $\mathcal{S}_{\mathcal{X}}(Λ)$. Similar consideration is also given for the singularity category of $\rm{mod}\mbox{-}\underline{\mathcal{X}}$.

math.RT↗
arXiv2019

Permutation codes over finite fields

In this paper we describe a class of codes called {\it permutation codes}. This class of codes is a generalization of cyclic codes and quasi-cyclic codes. We also give some examples of optimal permutation codes over binary, ternary, and $5$-ary. Then, we describe its structure as submodules over a polynomial ring.

cs.IT↗
arXiv2017

$Θ_S-$cyclic codes over $A_k$

We study $Θ_S-$cyclic codes over the family of rings $A_k.$ We characterize $Θ_S-$cyclic codes in terms of their binary images. A family of Hermitian inner-products is defined and we prove that if a code is $Θ_S-$cyclic then its Hermitian dual is also $Θ_S-$cyclic. Finally, we give constructions of $Θ_S-$cyclic codes.

cs.IT↗
arXiv2017

Skew-Cyclic Codes over $B_k$

In this paper we study the structure of $θ$-cyclic codes over the ring $B_k$ including its connection to quasi-$\tildeθ$-cyclic codes over finite field $\mathbb{F}_{p^r}$ and skew polynomial rings over $B_k.$ We also characterize Euclidean self-dual $θ$-cyclic codes over the rings. Finally, we give the generator polynomial for such codes and some examples of optimal Euclidean $θ$-cyclic codes.

math.CO↗
arXiv2010

Minimal Prime Ideals of Ore Extensions over Commutative Dedekind Domains

Let R = D[x;σ;δ] be an Ore extension over a commutative Dedekind domain D, where σis an automorphism on D. In the case δ= 0 Marubayashi et. al. already investigated the class of minimal prime ideals in term of their contraction on the coefficient ring D. In this note we extend this result to a general case δnot 0.

math.RA↗
arXiv2008

Braid action on derived category of Nakayama algebras

We construct an action of a braid group associated to a complete graph on the derived category of a certain symmetric Nakayama algebra which is also a Brauer star algebra with no exceptional vertex. We connect this action with the affine braid group action on Brauer star algebras defined by Schaps and Zakay-Illouz. We show that for Brauer star algebras with no exceptional vertex, the action is faithful.

math.RT↗
arXiv2005

Homomorphisms of complexes via homologies

By Rickard's work, two rings are derived equivalent if there is a tilting complex, constructed from projective modules over the first ring such that the second ring is the endomorphism ring of this tilting complex. In this work I describe, under some conditions, the homomorphism space in the derived category between two complexes as iterated pull-back of homomorphism spaces between the homologies of the complexes.

math.RA↗