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All Journal Electronic Journal of Graph Theory and Applications (EJGTA) Jurnal RESTI (Rekayasa Sistem dan Teknologi Informasi) BAREKENG: Jurnal Ilmu Matematika dan Terapan Math Educa Journal Jurnal Matematika UNAND Jurnal Saintika Unpam : Jurnal Sains dan Matematika Unpam Mandalika Mathematics and Educations Journal Limits: Journal of Mathematics and Its Applications
Syafrizal Sy
Departemen Matematika Dan Sains Data, FMIPA, Universitas Andalas
Chemistry Computer Science & IT Control & Systems Engineering Decision Sciences, Operations Research & Management Economics, Econometrics & Finance Electrical & Electronics Engineering Energy Engineering Mathematics Mechanical Engineering Physics Transportation

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Size multipartite Ramsey numbers for stripes versus small cycles Chula Janak Jayawardene; Edy Tri Baskoro; Lilanthi Samarasekara; Syafrizal Sy
Electronic Journal of Graph Theory and Applications (EJGTA) Vol 4, No 2 (2016): Electronic Journal of Graph Theory and Applications
Publisher : GTA Research Group, Univ. Newcastle, Indonesian Combinatorics Society and ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/ejgta.2016.4.2.4

Abstract

For simple graphs $G_1$ and $G_2$, the size Ramsey multipartite number $m_j(G_1, G_2)$ is defined as the smallest natural number $s$ such that any arbitrary two coloring of the graph $K_{j \times s}$ using the colors red and blue, contains a red $G_1$ or a blue $G_2$ as subgraphs. In this paper, we obtain the exact values of the size Ramsey numbers $m_j(nK_2, C_m)$ for $j \ge 2$ and $m \in \{3,4,5,6\}$.
BILANGAN RAMSEY MULTIPARTIT UKURAN UNTUK GRAF POHON DAN GRAF LINTASAN Yerti Syahraini Putri; Effendi Effendi; Syafrizal Sy
JURNAL SAINTIKA UNPAM Vol 3, No 2 (2021)
Publisher : Program Studi Matematika FMIPA Universitas Pamulang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32493/jsmu.v3i2.6675

Abstract

Misalkan j,l,n,s dan t adalah bilangan-bilangan asli dengan n,s≥2 dan j,l,t≥1 maka bilangan Ramsey multipartit ukuran m_j (K_(n×l),K_(s×t) )  adalah bilangan asli terkecil ξ sedemikian sehingga sebarang pewarnaan dari semua sisi K_(j×ξ)  menggunakan dua warna merah dan biru, akan selalu berlaku bahwa K_(j×ξ) memuat K_(n×l)  merah atau K_(s×t) biru sebagai subgraf. Untuk sebarang graf G dan H, j≥2 adalah bilangan bulat, bilangan Ramsey multipartit ukuran m_j (G,H)  adalah bilangan asli terkecil ξ sedemikian sehingga setiap faktorisasi dari graf K_(j×ξ)≔F_1⊕F_2 memenuhi kondisi berikut:  F_1 memuat subgraf G atau F_2 memuat subgraf H. Dalam makalah ini, akan ditentukan nilai-nilai dari bilangan Ramsey multipartit ukuran m_j (T_n,P_3 )  untuk j≥3. Hasil pada penelitian ini menunjukkan bahwa bilangan Ramsey multipartit ukuran untuk graf pohon dan graf lintasan, untuk sebarang bilangan bulat positif n dan j≥3, yaitu m_3 (T_n,P_3 )=⌈n/3⌉, m_4 (T_n,P_3 )=⌈n/4⌉, dan m_3 (T_j,P_3 )=⌈n/j⌉.
STABILITY ANALYSIS AND PERFORMANCE OF KALMAN FILTERING AND ROBUST KALMAN FILTERING ON UNCERTAIN CONTINUOUS-TIME SYSTEMS Rudianto, Budi; Muhafzan, Muhafzan; Syafwan, Mahdhivan; Sy, Syafrizal
BAREKENG: Jurnal Ilmu Matematika dan Terapan Vol 19 No 2 (2025): BAREKENG: Journal of Mathematics and Its Application
Publisher : PATTIMURA UNIVERSITY

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30598/barekengvol19iss2pp1295-1306

Abstract

This paper discusses the stability analysis of robust Kalman filtering on uncertain continuous-time systems. In real applications, systems often face model uncertainty and noise affecting prediction and estimation accuracy. Therefore, a filtering method is needed to overcome these uncertainties. Robust Kalman filtering is one of the most effective methods for dealing with model uncertainty. In this paper, we discuss the application of this method to continuous-time systems and its stability analysis. Simulation results show that robust Kalman filtering can provide more accurate and stable estimates than the conventional Kalman filter. Robust Kalman filtering can reduce the estimation error to about 30% under uncertain model conditions and maintain stability despite disturbances of up to 20% of the system parameters. However, this research has limitations regarding testing scenarios with more complex uncertainty models and higher disturbance variability. The originality of this research lies in its focus on the stability analysis of robust Kalman filtering on uncertain continuous-time systems, which has rarely been discussed in depth in previous literature.
SOFT GRAPHS OF THE BARBELL STAR GRAPH Helmi, Monika Rianti; Sy, Syafrizal; Nazra, Admi; Muhafzan; Hanifa, Nurul; Alfiany, Noverina
Jurnal Matematika UNAND Vol. 14 No. 4 (2025)
Publisher : Departemen Matematika dan Sains Data FMIPA Universitas Andalas Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jmua.14.4.366-375.2025

Abstract

\textit{Let $G^*=(V(G^*),E(G^*))$ is a simple graph and $A$ be a non-empty set of parameter. Let $R\subseteq A\times V(G^*)$ be a arbitrary relation from $A$ to $V(G^*)$. A mapping $F:A\to P(V(G^*))$ can be defined as $F(x)=\left\{y\in V\mid xRy \right\}$ and a mapping $K:A\to P(E(G^*))$ can be defined as $K(x)=\left\{uv\in E\mid \left\{u,v\right\}\subseteq F(x)\right\}$. A pair $(F,A)$ and $(K,A)$ are soft sets over $V(G^*)$ and $E(G^*)$ respectively, then $(F(a),K(a))$ is a subgraph of $G^*$. The 4-tuple $G=(G^*,F,K,A)$ is called a soft graph of $G$. In this paper, we enumerate soft graph of amalgamation of path and star.}
BILANGAN RAMSEY MULTIPARTIT HIMPUNAN (R-M-H) M_j(C_n, C_s) UNTUK CYCLE Majid, Abdul -; SY, SYAFRIZAL; NAZRA, ADMI
Jurnal Matematika UNAND Vol. 12 No. 4 (2023)
Publisher : Departemen Matematika dan Sains Data FMIPA Universitas Andalas Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jmua.12.4.309-317.2023

Abstract

Diberikan dua graf G dan H sembarang. Bilangan Ramsey multipartit himpunan (R-M-H) M_j(G, H) dengan bilangan asli j ≥ 2, adalah bilangan bulat positif terkecil t sedemikian sehingga jika semua sisi dari graf multipartit seimbang lengkap K_{t×j} diberi sebarang 2−pewarnaan merah-biru, maka graf K_{t×j} senantiasa memuat G berwarna merah sebagai subgraf atau H berwarna biru sebagai subgraf. Graf C_n adalah suatu graf cycle dengan n ≥ 3 titik. Pada artikel ini, Penulis akan menentukan bilangan R-M-H M_j(C_n, C_s) untuk sebarang bilangan asli n ≥ 3 ganjil dan s ≥ 3. Hasil dari penelitian ini adalah ditemukannya bilangan R-M-H Mj (C_n, C_s) untuk cycle.
BILANGAN R-M-H UNTUK GRAF LINTASAN P_4 DAN GRAF RODA W_n DENGAN n>=3 Multasya, Nadya Citra; SYAFWAN, MAHDHIVAN; SY, SYAFRIZAL
Jurnal Matematika UNAND Vol. 12 No. 2 (2023)
Publisher : Departemen Matematika dan Sains Data FMIPA Universitas Andalas Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jmua.12.2.135-143.2023

Abstract

Diberikan dua graf G dan H serta bilangan asli j>=2. Bilangan Ramsey multipartit himpunan (R-M-H) M_j(G,H) adalah suatu bilangan bulat positif terkecil t sedemikian sehingga untuk sebarang faktorisasi K_(txj) = F_1 + F_2 senantiasa F_1 memuat subgraf G atau F_2 memuat subgraf H. Pada artikel ini akan ditentukan M_3(P_4,W_n) dimana P_4 adalah suatu graf lintasan yang terdiri dari 4 simpul dan W_n adalah suatu graf roda yang terdiri dari n+1 simpul dengan n>=3.
Bilangan Kromatik Lokasi Graf Tentakel Azizah Riana Putri; Syafrizal Sy; Monika Rianti Helmi
Limits: Journal of Mathematics and Its Applications Vol. 22 No. 2 (2025): Limits: Journal of Mathematics and Its Applications Volume 22 Nomor 2 Edisi Ju
Publisher : Pusat Publikasi Ilmiah LPPM Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/limits.v22i2.3462

Abstract

The locating-chromatic number of a graph was introduced by Chartrand et al. in 2002, which is a combined concept between the vertex coloring and partition dimension of a graph. The locating-chromatic number of a graph is a grouping of vertices on a graph based on color, which is called a color class, provided that each vertex on the graph has a different color code. Determining the locating-chromatic number of a graph is done by constructing the lower and upper bound of the locating-chromatic number of the graph. In this paper, we determine the locating-chromatic number of the tentacle graph, which is denoted by T_(k,m,n). Tentacle Graph is a graph constructed from a triangular book graph Bt_n whose common edge is amalgamated with C_k. Then two vertices in C_k that are adjacent to the vertex associated with the terminal edge are amalgamated with the star graphs S_(n_1) and S_(n_2). By determining the lower and upper bounds of the location chromatic number, it is obtained that the location chromatic number of Tentacle Graph is 4, m=1,n=2, n+1, for m>=1, n>= m + 2, and m + 2, for m > 1, n < m + 2.
Bilangan Kromatik Lokasi Graf Amal(K_n, K_m) Syafrizal Sy; Rizki Ladipa YM; Monika Rianti Helmi
Limits: Journal of Mathematics and Its Applications Vol. 21 No. 3 (2024): Limits: Journal of Mathematics and Its Applications Volume 21 Nomor 3 Edisi No
Publisher : Pusat Publikasi Ilmiah LPPM Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

Misalkan G adalah pasangan terurut (V, E), yaitu graf terhubung, dan c adalah suatu pemetaan warna pada graf G yang didefinisikan sebagai c dari V(G) ke himpunan {1, 2, ..., t}, dengan t adalah bilangan asli. Jika simpul u dan v bertetangga di G, maka c(u) tidak sama dengan c(v). Misalkan S_h adalah himpunan simpul yang diberi warna h untuk setiap h anggota {1, 2, ..., t}, maka S_h disebut kelas warna. Misalkan Pi adalah partisi dari himpunan simpul V(G) yaitu Pi = {S_1, S_2, ..., S_t} untuk suatu pewarnaan. Kode warna c_Pi dari simpul v dalam G didefinisikan sebagai vektor dengan t komponen yaitu c_Pi(v) = (d(v, S_1), d(v, S_2), ..., d(v, S_t)), di mana d(v, S_h) adalah jarak minimum antara v dan setiap simpul x dalam S_h, yaitu d(v, S_h) = minimum dari d(v, x) untuk x dalam S_h, dan h dari 1 sampai t. Jika setiap simpul dalam G memiliki kode warna yang berbeda untuk suatu partisi Pi, maka pewarnaan c disebut sebagai pewarnaan lokasi. Nilai minimum dari t sedemikian sehingga G memiliki pewarnaan lokasi dengan t warna disebut sebagai bilangan kromatik lokasi, dan dinotasikan dengan chi sub L dari G. Dalam penelitian ini dibahas tentang bilangan kromatik lokasi dari graf Amal(K_n, K_m). Graf Amal(K_n, K_m) adalah graf yang dibentuk dengan menggabungkan satu simpul di setiap graf lengkap K_n ke setiap simpul di graf lengkap K_m secara satu-satu, dengan syarat m dan n lebih besar atau sama dengan 2, dan m serta n adalah bilangan asli. Dengan menentukan batas bawah dan batas atas bilangan kromatik lokasi, diperoleh bahwa bilangan kromatik lokasi dari graf Amal(K_n, K_m) adalah: sebesar n + 1 jika m lebih kecil atau sama dengan n, dan sebesar m jika m lebih besar dari n
RAINBOW CONNECTION NUMBERS IN GRAPHS: A COMPREHENSIVE STUDY Gema Hista Medika; Syafrizal Sy; Muhafzan Muhafzan; Zulfaneti Zulfaneti
Math Educa Journal Vol 10, No 1 (2026)
Publisher : UIN Imam Bonjol Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15548/mej.v10i1.13681

Abstract

The rainbow connection number is a graph parameter that integrates edge colouring and graph connectivity. A connected graph is said to be rainbow connected if every pair of vertices is joined by a path whose edges have distinct colours, and the rainbow connection number represents the minimum number of colours required to satisfy this property. This study aims to provide a comprehensive and systematic analysis of research developments related to rainbow connection numbers in graphs. The method employed is a systematic literature review of reputable international journals and nationally accredited publications. The analysis covers fundamental definitions, known values for various classes of graphs, relationships with structural parameters such as diameter, minimum degree, and connectivity, as well as computational complexity and several important variants, including strong rainbow connection, rainbow vertex-connection, and total rainbow connection. The results indicate that the rainbow connection number is strongly influenced by graph structure, with diameter serving as a natural lower bound and connectivity contributing to tighter upper bounds. Furthermore, determining the exact value for general graphs is computationally intractable, motivating the use of approximation and heuristic approaches. This study also identifies research gaps, particularly in algorithmic development and the analysis of complex graph class, and highlights potential applications in communication networks and network security.
Eksistensi dan Keunikan dalam Pengendalian LQ Berhorison Tak Terbatas Melalui Analisis Riccati Berbasis Sontag Budi Rudianto; Muhafzan Muhafzan; Mahdhivan Syafwan; Syafrizal Sy
Mandalika Mathematics and Educations Journal Vol 8 No 1 (2026): Edisi Maret
Publisher : FKIP Universitas Mataram

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29303/jm.v8i1.10782

Abstract

This paper examines the existence and uniqueness of solutions to Linear Quadratic (LQ) optimal control problems with infinite time horizons in time-varying dynamic systems. By extending Sontag's Theorem to semi-infinite intervals, the properties of The Riccati Differential Equation’s solutions are analyzed under assumptions of essential boundedness and boundedness of the system matrix and cost weights. It is proven that the Riccati matrix solution P(t) exists globally, remains positive definite, and converges to the steady-state limit P∞. The uniqueness of the optimal control–state pair (x,u) is obtained through P(t)-based co-state analysis. Simulations on satellite attitude control systems demonstrate convergence and robustness towards periodic disturbances, supporting applications in adaptive control, robust estimation, and time-varying filtering.
Co-Authors - Primawati Adiwijaya Admi Nazra Alfiany, Noverina Azizah Riana Putri Budi Rudianto Chula Janak Jayawardene Edy Tri Baskoro Effendi Effendi Fazrol Rozi, Fazrol Gema Hista Medika Hanifa, Nurul Helmi, Monika Rianti Lilanthi Samarasekara Majid, Abdul - Muhafzan Muhafzan Muhafzan Multasya, Nadya Citra Nurwijayanti Rizki Ladipa YM Syafwan, Mahdhivan Yerti Syahraini Putri Yusrawati Yusrawati Zulfaneti Zulfaneti