Judul: Relationship of Coral Reef Health and Community Welfare ( a Case Study of Tidung Island, Seribu Islands)
Abstrak: Keberadaan terumbu karang menjadikan Pulau Tidung sebagai pulau kecil yang berkembang ke arah wisata bahari, hal ini dapat mengakibatkan perubahan lingkungan dan masyarakat. Ekosistem terumbu karang di sekitar Pulau Tidung telah dimanfaatkan oleh masyarakat sekitar. Penelitian ini bertujuan untuk menganalisis keterkaitan kesehatan terumbu karang berdasarkan persen tutupannya terhadap kesejahteraan masyarakat Pulau Tidung. Penelitian ini dilakukan pada bulan Juli 2019 dan Juni 2020. Data primer diperoleh dengan mewawancarai masyarakat Pulau Tidung mengenai aspek-aspek kesejahteraan menurut BPS 2015. Data sekunder meliputi data ekosistem terumbu karang berupa persentase tutupan karang dan jumlah lifeform didapatkan dari hasil penelitian Adrianto et al. 2019. Data hasil penelitian berupa status kesehatan terumbu karang dan tingkat kesejahteraan masyarakat dianalisis dengan metode deskriptif untuk menjawab tujuan penelitian. Hasil penelitian ini menunjukkan status terumbu karang di sebelah selatan dan sebelah utara Pulau Tidung berturut turut adalah buruk dan sedang. Kualitas terumbu karang tidak mempengaruhi tingkat kesejahteraan masyarakat di Pulau Tidung.
Keyword: poverty, community welfare, Tidung Island, coral reefs

Judul: Coral Reef Ecosystem Rehabilitation Strategy on Tidung Island, Seribu Island for Supporting Ecotourism Development
Abstrak: Ekosistem terumbu karang yang terdapat di sekitar Pulau Tidung, Kepulauan Seribu dimanfaatkan oleh masyarakat untuk menjadi obyek wisata, pemanfaatan yang dilakukan secara terus menerus harus dilakukan dengan pengelolaan yang sesuai agar dapat berkelanjutan. Penelitian ini bertujuan untuk menganalisis efektivitas strategi rehabilitasi ekosistem terumbu karang di Pulau Tidung untuk perancangan pengembangan ekowisata. Data yang digunakan didapatkan melalui studi literatur dan wawancara. Analisis data yang digunakan di antaranya Meta-Analisis dan Analytical Network Process (ANP). Hasil review data menunjukkan terjadinya pemulihan pada ekosistem terumbu karang di lokasi penelitian. Penelitian oleh Fauzanbahri et al. (2021) pada tahun 2018 menunjukkan bahwa nilai persentase tutupan karang keras hanya sebesar 14,79% dan meningkat pada tahun 2021 menjadi sebesar 30,65%. Hasil wawancara dengan pihak pengelola menjelaskan bahwa strategi rehabilitasi yang diterapkan di Pulau Tidung di antaranya dengan melakukan penanaman kembali, pengembangan budidaya karang dan adopsi karang bagi wisatawan serta menerapkan pembagian zonasi bagi wilayah rehabilitasi dan wilayah pemanfaatan. Strategi rehabilitasi ini dinilai cukup efektif karena telah terjadi pemulihan pada ekosistem terumbu karang sebesar 5,23% per-tahun. Selanjutnya, pengembangan ekowisata di Pulau Tidung dirancang dengan berbasis ekologi dan memiliki fokus utama pada sosial budaya. Hal ini bertujuan untuk melibatkan partisipasi terhadap pengelolaan wisata., As a tourist attraction, the surrounding community utilizes coral reef ecosystems around Tidung Island, Thousand Island; continuous use must be carried out with appropriate management to be sustainable. This study aims to analyze the effectiveness of coral reef ecosystem rehabilitation strategies on Tidung Island for designing ecotourism development. The data used was obtained through literature and interviews. Data analysis used includes Meta-Analysis and Analytical Network Process (ANP). The results of the research in the form of a data review show recovery in the coral reef ecosystem. According to research by Fauzanbahri et al. (2021), the percentage value of hard coral cover was only 14.79% in 2018 and increased in 2021 to 30.65%. The results of interviews with the stakeholders explained that the rehabilitation strategy implemented on Tidung Island included replanting coral cultivation and adoption for tourists and implementing zoning divisions for rehabilitation and utilization areas. This rehabilitation strategy was considered quite effective because the coral reef ecosystem has recovered. This rehabilitation strategy is considered quite effective because the coral reef ecosystem has recovered with a recovery rate of approximately 5,23% per year. Furthermore, Tidung Island is designed ecologically and mainly focuses on socio-culture. Ecotourism development aims to involve participation in tourism management.
Keyword: Coral Ecosystem, Utilization, Tidung Island

Judul: The Construction of Greedy SVP LLL Algorithm
Abstrak: A lattice is a set of all integer linear combination of a set of linearly independent vectors in ℝ𝑛���. The independent vectors are called bases of lattice. Any lattice can be generated from many bases, and these bases have the same cardinality. In the lattice, the most fundamental and renowned problem is the Shortest Vector Problem (SVP). SVP is a tracking problem of the shortest nonzero vector in a lattice with equivalent bases. In two dimensions, SVP problem has resolved exactly by Gauss’ algorithm. When the lattice dimension is higher than two, A.K. Lenstra, H.W. Lenstra and L. Lovasz gave a LLL algorithm to compute approximation of nonzero shortest vector in the lattice. Reduced bases solution obtained from LLL algorithm still be an approximation and has polynomial running time of arbitrary dimension which large enough. In 1994, Schnoor and Euchner modified this LLL algorithm as a new variant which later was named deep insertion LLL algorithm. This algorithm is a modified version of the LLL algorithm to the terms of the exchange step to improve the accuracy of output of LLL reduced bases and applying it to the subset sum problem. The purpose of this research are: (1) Reconstruct the LLL algorithm and deep insertion LLL algorithm using a geometric approach. (2) Construct a greedy SVP LLL algorithm. (3) Implement the three algorithms in a symbolic programming language, and evaluate them experimentally. A bases ℬ=[𝐛���1,𝐛���2,…,𝐛���𝑛���] in ℝ𝑚��� is called reduced LLL with parameter 𝛿��� if satisfies: (a) |𝜇���𝑗���𝑖���|≤12, for every integer 𝑖���,𝑗��� with 1≤𝑖���<𝑗���<𝑛���. (b)𝛿���‖𝜋���𝑗���(𝐛���𝑗���)‖2≤‖𝜋���𝑗���(𝐛���𝑗���+1)‖2, for 𝑗���=1,2,…,𝑛���−1,where 𝛿��� is a reduced parameter of real numbers with 14<𝛿���<1. The first requirement is the reduced basis 𝛿��� must “nearly orthogonal” and in its computation case, this requirement can be reached out by using the Gram-Schmidt’s orthogonalization. While the second requirement is called exchange step, or used to called as Lovasz condition. By using both of these requirements, then they establish the LLL algorithm. Then, Schnoor and Euchner modify the LLL algorithm based on the requirements of the exchange step called the deep insertion LLL algorithm, where the exchange step is based on the comparison of the projected vector in orthogonal complement [𝐛���1,𝐛���2,…,𝐛���𝑘���−1]⊥ after j-th reduction. To construct greedy SVP LLL algorithm, the requirements of the exchange step is based on purely by comparing norm of lattice 𝐛���𝑗��� with norm lattice 𝐛���𝑖��� for 𝑖���=1,2,3…,𝑗���−1. The process of insertion reduced vector after the exchange step also has done greedily. Then, we calculate the number of arithmetic operation in greedy SVP LLL algorithm for further analysis. The result of our exprimentation for three algorithms on the certain matrix size shows that the running time of the three algorithms increases propotional to the size of the matrix. The result also shows that by using 𝛿���=34 for the LLL algorithm and the deep insertion LLL algorithm, and the greedy SVP LLL algorithm which is a new variant made by using no parameter of 𝛿���, outperform of the other of two previous algorithm in terms of speed with the same output.
Keyword: LLL algorithm, LLL deep insertion algorithm, greedy SVP LLL algorithm