Judul: Studi Kasus di Kecamatan Cengkareng, Kotamadya Jakarta Barat
Abstrak: Beras merupakan makanan pokok masyarakat Indonesia. Persepsi masyarakat tentang keberadaan beras serta perubahan pola konsumsi dalam masyarakat setelah mencapai swasen,bada beras menyebabkan konsurnsi beras cenderung meningkat setiap tahunnya, yaitu rata-rata 0,25% per tahun (Pusat Promosi dan Informasi Tanaman Pangan dan Hortikultura, 1998). Besarnya konsumsi beras pada masyarakat. Indonesia dapat dilihat pada besarnya pengeluaran konsumen untuk membeli kebutuhan pangan. Pada tahun 1999 jenis makanan yang berasal dad padi (beras), menempati posisi kedua yakni sebesar Rp 11.136,- setelah produk makanan dan minuman jadi sebesar Rp 14.764,- per hari. Hal ini membuktikan bahwa beras tetap merupakan pilihan pangan untuk dikonsumsi sehari-hari.
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Judul: Analisis Preferensi dan Kepuasan Konsumen terhadap Beras Di Kecamatan Mulyorejo Surabaya Jawa Timur
Abstrak: Bustaman (2003) menyatakan bahwa beras sangat penting terkait jumlah produsen dan konsumennya di Indonesia. Dari sisi produsen, usahatani padi di Indonesia melibatkan 25,4 juta rumah tangga. Sedangkan dari sisi konsumen, lebih dari 90 persen penduduk Indonesia mengkonsumsi beras, bahkan 30 persen dari total pengeluaran rumah tangga miskin dipergunakan untuk membeli beras. Ini menunjukkan posisi beras yang sangat strategis sebagai penopang ketahanan pangan di Indonesia, stabilitas ekonomi, dan lapangan kerja. Konsumsi beras perkapita yang tinggi, disertai jumlah penduduk Indonesia yang sebagian besar mengkonsumsi beras menyebabkan total konsumsi beras nasional yang tinggi setiap tahunnya. Bagi negara dengan kebutuhan beras yang besar seperti Indonesia, bergantung pada pasar impor jelas berisiko.
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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