Complexity of Discrete Energy Minimization Problems

Discrete energy minimization is widely-used in computer vision and machine learning for problems such as MAP inference in graphical models. The problem, in general, is notoriously intractable, and finding the global optimal solution is known to be NP-hard. However, is it possible to approximate this problem with a reasonable ratio bound on the solution quality in polynomial time? We show in this paper that the answer is no. Specifically, we show that general energy minimization, even in the 2-label pairwise case, and planar energy minimization with three or more labels are exp-APX-complete. This finding rules out the existence of any approximation algorithm with a sub-exponential approximation ratio in the input size for these two problems, including constant factor approximations. Moreover, we collect and review the computational complexity of several subclass problems and arrange them on a complexity scale consisting of three major complexity classes -- PO, APX, and exp-APX, corresponding to problems that are solvable, approximable, and inapproximable in polynomial time. Problems in the first two complexity classes can serve as alternative tractable formulations to the inapproximable ones. This paper can help vision researchers to select an appropriate model for an application or guide them in designing new algorithms.Comment: ECCV'16 accepte

Pembangunan sistem informasi reservasi di gua Kerep Abarawa

Reservasi yang terjadi di GMKA masih menggunakan sistem pencatatan manual untuk pemesanan tempat. Pencatatan manual terkadang ditemukan kesalahan yang disebabkan oleh karyawan atau penggelola (human error). Tim pengelola Gua Maria Kerep Ambarawa berencana untuk membangun sistem baru yang dapat menangani masalah ini. Sistem yang telah ada dan dipergunakan oleh pengelola Gua Maria Kerep Ambarawa memiliki fungsi untuk menampilkan informasi tentang jadwal novena yang dilakukan di GMKA, dan beberapa informasi mengenai GMKA. Sistem yang telah dipergunakan oleh GMKA tidak menangani proses pemesanan tempat. Masalah ini dapat dipecahkan dengan membangun sebuah sistem informasi berbasis web yang memungkinkan untuk melakukan pemesanan tempat. Sistem informasi ini berisi dengan informasi dari Gua Maria Kerep Ambarawa dan sistem ini dapat dengan mudah untuk melakukan proses pemesanan tempat. Sistem informasi ini dibangun dengan memanfaatkan framework CodeIgniter, menggunakan database MySql, bahasa PHP dan untuk pengembangannya menggunakan XAMPP dan Notepad ++ Dengan tercipta sistem ini, pengelola Gua Maria Kerep Ambarawa dapat mengatasi masalah dalam menangani proses pemesanan tempat

Far-Field Modeling of a Deep-Sea Blowout: Sensitivity Studies of Initial Conditions, Biodegradation, Sedimentation, and Subsurface Dispersant Injection on Surface Slicks and Oil Plume Concentrations

Modeling of large-scale oil transport and fate resulting from deep-sea oil spills is highly complex due to a number of bio-chemo-geophysical interactions, which are often empirically based. Predicting mass-conserved total petroleum hydrocarbon concentrations is thus still a challenge for most oil spill models. In addition, dynamic quantification and visualization of spilled oil concentrations are necessary both for first response and basin-wide impact studies. This chapter presents a new implementation of the Connectivity Modeling System (CMS) oil application that tracks individual multi-fraction oil droplets and estimates oil concentrations and oil mass in a 3D space grid. We used the Deepwater Horizon (DWH) blowout as a case study and performed a sensitivity analysis of several modeling key factors, such as biodegradation, sedimentation, and alternative initial conditions, including droplet size distribution (DSD) corresponding to an untreated and treated live oil from subsurface dispersant injection (SSDI) predicted experimentally under high pressure and by the VDROP-J jet-droplet formation model. This quantitative analysis enabled the reconstruction of a time evolving three-dimensional (3D) oil plume in the ocean interior, the rising and spreading of oil on the ocean surface, and the effect of SSDI in shifting the oil to deeper waters while conserving the mass balance. Our modeling framework and analyses are thus important technical advances for understanding and mitigating deep-sea blowouts

Isolated Neutral Peptides

International audienc