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Contemporary Mathematics and Applications (ConMathA)
Published by Universitas Airlangga
ISSN : -     EISSN : 26865564     DOI : https://doi.org/10.20473/conmatha
Core Subject : Science, Education,
Materials Science & Nanotechnology Mathematics
Contemporary Mathematics and Applications welcome research articles in the area of mathematical analysis, algebra, optimization, mathematical modeling and its applications include but are not limited to the following topics: general mathematics, mathematical physics, numerical analysis, combinatorics, optimization and control, operation research, statistical modeling, mathematical finance and computational mathematics.
Arjuna Subject : Matematika - Matematika (Lain-Lain)
Articles 76 Documents
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Implementation of Mamdani Method Fuzzy System in Determining Final Semester Grades of UIN Walisongo Semarang Students Rezky Aprilianto, Arif; Budi Cahyono; Mohamad Tafrikan
Contemporary Mathematics and Applications (ConMathA) Vol. 7 No. 1 (2025)
Publisher : Universitas Airlangga

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20473/conmatha.v7i1.53479

Abstract

Final semester grades are an important component for students to obtain a pass in completing a course. The program for determining final semester grades using fuzzy Mamdani can be used to facilitate the calculation of final semester grades. This research aims to determine the results of applying the Mamdani fuzzy system method in determining the final semester grades of students at UIN Walisongo Semarang. The Mamdani fuzzy system method was chosen as the method for calculating final semester grades along with MAPE (Mean Absolute Percentage Error) calculations. In accordance with the lecture contract for the computational mathematics course, several input variables were found to be used in the research, namely structured assignment grades (20%), independent assignment grades (30%), mid-semester exam grades (25%), and final semester exam scores (25%). The data is processed in several steps, namely creating fuzzy membership sets and functions, creating fuzzy rules, fuzzification, and defuzzification. After calculating with the Mamdani method fuzzy system, the next step is to calculate the MAPE value and display the results. The MAPE value obtained from research with 46 data was 2.074; This means that according to the MAPE criteria it produces accurate data. This proves that the Mamdani fuzzy system method can be applied to calculate students' final semester grades.
Application of the ARIMA-GARCH Model for Forecasting Indonesia's Monthly Inflation Rate Anisa; Yudistira, Ira; Yulianto, Tony
Contemporary Mathematics and Applications (ConMathA) Vol. 7 No. 1 (2025)
Publisher : Universitas Airlangga

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20473/conmatha.v7i1.60263

Abstract

Inflation is one of the important aspects that is used as a benchmark to see economic growth and economic conditions in each country. Inflation has resulted in increasing public expenditure in meeting basic needs. Inflation must be controlled to maintain the economic stability of a country, including Indonesia. Therefore, there is a need for a model that can forecast the inflation rate in Indonesia. The aim of this research is to create a model that can predict future inflation levels so that it can help the government in determining policies related to controlling inflation in Indonesia. The data used is monthly inflation data in Indonesia for 19 years from March 2007- October 2023 in percentage form. The forecasting model used in this study is the ARIMA-GARCH model. The ARIMA model is a time series model used to forecast future data based on past data. While GARCH is a time series model used to overcome heteroscedasticity in the ARIMA model. Inflation data will be modeled using the ARIMA model and then continued by modeling the residuals using the GARCH model if heteroscedasticity occurs in the ARIMA model residuals. Based on data analysis that has been done, the best model for inflation forecasting cases in Indonesia is the ARIMA (2,0,2) - GARCH (0,1) model with a MAPE value of 17.78%.
The Szeged Index and Padmakar-Ivan Index on the Zero-Divisor Graph of a Commutative Ring Ambar, Jinan; I Gede Adhitya Wisnu Wardhana; Abdurahim
Contemporary Mathematics and Applications (ConMathA) Vol. 7 No. 1 (2025)
Publisher : Universitas Airlangga

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20473/conmatha.v7i1.63517

Abstract

The zero-divisor graph of a commutative ring is a graph where the vertices represent the zero-divisors of the ring, and two distinct vertices are connected if their product equals zero. This study focuses on determining general formulas for the Szeged index and the Padmakar-Ivan index of the zero-divisor graph for specific commutative rings. The results show that for the first case of ring, the Szeged index is exactly half of the Padmakar-Ivan index. For the second case, the Szeged index is consistently greater than the Padmakar-Ivan index. These findings enhance the understanding of how the algebraic structure of rings influences the topological properties of their associated graphs.
Determining Optimal Hierarchical Clustering by Combining Needleman Wunsch and Jukes Cantor Algorithms in Tuberculosis (TB) Disease Clustering Hildatul Anizah; Tony Yulianto; Kuzairi; Ira Yudistira; Amalia, Rica
Contemporary Mathematics and Applications (ConMathA) Vol. 7 No. 1 (2025)
Publisher : Universitas Airlangga

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20473/conmatha.v7i1.64172

Abstract

Tuberculosis (TBC) is an infectious disease affecting the respiratory system, caused by the bacterium Mycobacterium tuberculosis. Tuberculosis (TBC) remains a global concern, and to date, no country is completely free from TB. This disease continues to be one of the leading causes of mortality. Therefore, it is essential to categorize the spread of TBC. The percentage of identity in genetic codes will reveal the proportion of mutations. The percentage of identity in genetic codes will demonstrate that, although the symptoms caused by a disease may be quite similar, the protein sequences are not necessarily the same. In this study, the researchers employed the Hierarchical Clustering method, integrating the Needleman-Wunsch and Jukes-Cantor algorithms, resulting in two groups. The first group consists of 9 interconnected rows, while the second group consists of 7 interconnected rows.
Voice-Based Emotion Identification Based on Mel Frequency Cepstral Coefficient Feature Extraction Using Self-Organized Maps and Radial Basis Function Nikmah, Asrivatun; Damayanti, Auli; Winarko, Edi
Contemporary Mathematics and Applications (ConMathA) Vol. 7 No. 1 (2025)
Publisher : Universitas Airlangga

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20473/conmatha.v7i1.68246

Abstract

Speech recognition is one of the most popular research fields, one of which is about emotion identification. Voice-based emotion identification is carried out to determine the pattern of emotions using the depth analysis mechanism of voice signal development and feature extraction that carries the emotional characteristic parameters of the speaker's voice. Furthermore, the emotional characteristics of the speaker's voice are classified using an artificial neural network method to recognize patterns. In this study, emotion identification from voice signal data is classified into angry, sad, happy, and neutral emotions. The stages of voice-based emotion identification, including the feature extraction stage using the mel frequency cepstral coefficient, produce coefficient values, which will be used in the identification stage using the Self Organized Maps method on the Radial Basis Function.
Analysis of Land Surface Temperature Changes in East Lombok Regency Using the Cloud-Based Platform Google Earth Engine Dani, Ifan Hasnan; Hardi, Rida Alkausar; Al Paqih, Muhammad Imam; Ulfa, Kurnia; Robbaniyyah, Nuzla Af'idatur; Alfian, Muhammad Rijal
Contemporary Mathematics and Applications (ConMathA) Vol. 7 No. 2 (2025)
Publisher : Universitas Airlangga

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20473/conmatha.v7i2.68243

Abstract

This study uses Google Earth Engine, a cloud computing platform, to examine variations in land surface temperature in East Lombok Regency between 2010 and 2020. This study uses MODIS satellite data and is analyzed using Google Earth Engine by adapting a mathematical method—namely, the Random Forest Algorithm from discrete mathematics. According to the results, the temperature increased from its lowest point in 2010 (14.32°C) to its maximum point in 2020 (36.19°C), rising to 16.67°C and 37.74°C. Due to residential growth, Wanasaba, Pringgabaya, and Sambelia saw the biggest increases. Comprehensive temperature monitoring is made possible by Google Earth Engine, which facilitates the effective processing of large-scale spatial data. These results offer a scientific foundation for policy decisions and are essential for environmental management and climate change mitigation. In addition to supporting environmental monitoring initiatives, this study provides a reference for related studies in other areas dealing with issues related to land use and climate change. This research is important for the Central Lombok government as a basis for mitigation efforts in responding to temperature changes and their implications for land use change.
Numerical Invariants Of Nilpotent Graphs In Integer Modulo Rings Malik, Deny Putra; Karang, Gusti Yogananda; Aini, Qurratul; Maulana, Fariz; Satriyantara, Rio
Contemporary Mathematics and Applications (ConMathA) Vol. 7 No. 2 (2025)
Publisher : Universitas Airlangga

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20473/conmatha.v7i2.69650

Abstract

Graph theory offers a robust framework for examining algebraic structures, especially rings and their elements. This paper focuses on the nilpotent graph of rings of the form Zpk​, where p is a prime and k∈N, investigating both their structural and numerical properties. We begin by characterizing the nilpotent elements in these rings and examining their relationship to ring ideals. The study then presents theoretical results on key graph invariants, including connectivity, chromatic number, clique number, and specific subgraph configurations. To complement these, we also analyze numerical invariants such as edge count and degree distribution, which reveal deeper connections between ring-theoretic and graph-theoretic properties. Our results highlight consistent structural patterns in nilpotent graphs of Zpk ​and provide a concrete contribution to algebraic graph theory by bridging properties of commutative rings and their associated graphs.
Comparison of Double Exponential Smoothing and Double Moving Average for Forecasting Lost Vehicle Registration Certificates in Pamekasan Ramadani, Nia; Faisol; Kuzairi; Amalia, Rica
Contemporary Mathematics and Applications (ConMathA) Vol. 7 No. 2 (2025)
Publisher : Universitas Airlangga

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20473/conmatha.v7i2.70201

Abstract

The government issues the Vehicle Registration Certificate (STNK), an official document that certifies a motorized vehicle's identity and authenticity. Pamekasan Regency is one of the regencies in East Java Province that frequently suffers losses associated with Vehicle Registration Certificates (STNK). Consequently, it is essential to predict the amount of car registration losses so that the Pamekasan regional administration can use the information to lower the losses. The Double Exponential Smoothing and Double Moving Average techniques were used in this study to forecast the amount of vehicle registration losses. According to the research findings, the smoothing parameters ? = 0.3 and ? = 0.025 had the lowest MAPE value from the Double Exponential Smoothing method, with a MAPE value of 49.4082%. The double moving average method's smallest MAPE, ? = 3, has a MAPE value of 31.53215%. The twofold moving average approach is the best way to forecast the loss of car registration in Pamekasan, according to the comparison's findings.
Pattern-Based Identification of Priority Sectors for Greenhouse Gas Emission Control in Indonesia Using Self-Organizing Map Nurdini, Aisyah Tur Rif’atin; Amiroch, Siti
Contemporary Mathematics and Applications (ConMathA) Vol. 7 No. 2 (2025)
Publisher : Universitas Airlangga

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20473/conmatha.v7i2.74176

Abstract

Indonesia is one of the countries that ratified the Paris Agreement, a legally binding international treaty under the United Nations Framework Convention on Climate Change (UNFCCC) regarding greenhouse gas emissions. In line with this commitment, Indonesia is expected to prioritize emission control in sectors that contribute significantly to national emission levels. This study applies the Self-Organizing Map (SOM), a type of neural network, to cluster emission data by sector based on similarity patterns, aiming to identify priority sectors for emission control in Indonesia. The results indicate that the highest-emitting sectors are: Processes for Carbon Dioxide (CO₂), Transport for Methane (CH₄), Processes for F-Gases, and Agriculture for Nitrous Oxide (N₂O). These findings can inform government efforts to prioritize emission control policies in the Processes, Transport, and Agriculture sectors, tailored to each dominant gas type. Such recommendations are essential to support data-driven decision-making, improve national emission control strategies, and strengthen Indonesia’s position in meeting its Nationally Determined Contributions (NDCs) under the Paris Agreement. Model validation using Quantization Error (QE) produced values of 0.0218 for CO₂, 0.0207 for CH₄, 0.0040 for F-Gases, and 0.0171 for N₂O. These low values indicate high mapping accuracy and confirm that SOM is effective in capturing the distribution patterns of emission data, thus providing a scientific basis for designing more targeted mitigation strategies.  
Efficiency Measurement of Subsidized Fertilizer Use on Rice Crop Yields in Bangsri District using Data Envelopment Analysis Fata, Hafidh Khoerul; Maharani, Keysa Andinar
Contemporary Mathematics and Applications (ConMathA) Vol. 7 No. 2 (2025)
Publisher : Universitas Airlangga

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20473/conmatha.v7i2.74568

Abstract

This study evaluates the technical efficiency of subsidized fertilizer use in rice production across villages in Bangsri Sub-district, Jepara Regency, using the output-oriented CCR model of Data Envelopment Analysis (DEA). The research was motivated by the crucial role of fertilizers in sustaining rice productivity and the persistent issue of inefficient allocation and utilization of subsidized inputs. Secondary data for 2023 were obtained from the Balai Penyuluh Pertanian of Bangsri Sub-district and the Badan Pusat Statistik of Central Java. Input variables included the quantity of subsidized urea, NPK, and granular organic fertilizers, as well as cultivated land area; the output variable was rice production, calculated under the assumption of constant provincial average productivity of 49.26 quintals/ha. All villages in the sub-district were treated as Decision-Making Units (DMUs). The DEA results revealed that only Kedungleper achieved full efficiency (score = 1.00), while Jerukwangi was near the frontier (score = 0.96). Most villages scored between 0.80 and 0.89, indicating substantial room for optimization. The observed inefficiencies may be attributed to mismatches in fertilizer dosage and composition, suboptimal timing and application methods, and local agronomic constraints. Recommended strategies include benchmarking efficient villages, revising fertilization packages and schedules based on site-specific conditions, and strengthening plot-level extension services to ensure that inputs are effectively translated into yield gains. These findings provide actionable insights for improving resource-use efficiency and guiding targeted fertilizer subsidy policies.

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