27 research outputs found
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
Liberating Native Mass Spectrometry from Dependence on Volatile Salt Buffers by Use of Gábor Transform
Influence of zeolite nanofillers on properties of polymeric materials
The present work deals with the preparation and study of modified polymeric materials with the replacement of carbon black by nanofillers on the basis of zeolite that is environmentally friendly. Natural zeolites from a group of
aluminosilicate nanoporous materials have wide range of possibilities for applications that are environmentally friendly. Zeolites can be used in the role of fillers into the polymer materials too [1]. The given work deals with the preparation
and study of modified polymeric materials with the substitution of carbon black by
nanofillers on the basis of monoionic form - Ni(II) zeolite. The prepared monoinic
forms – Ni(II) zeolite were characterized by the method of infrared spectroscopy.
The vulcanization performance of prepared modified polymeric compounds and
physical-mechanical properties of vulcanizates were measured and the efficiency of
zeolite filler and carbon black filler was evaluated. The obtained values were
compared with the values of commercially used polymer materials with the original
composition
Mechanical properties and thermal stability of Al-23Si-8Fe-1Cr and Al-23Si-8Fe-5Mn alloys prepared by powder metallurgy
Linear-time limited automata
The time complexity of 1-limited automata is investigated from a descriptional complexity view point. Though the model recognizes regular languages only, it may use quadratic time in the input length. We show that, with a polynomial increase in size and preserving determinism, each 1-limited automaton can be transformed into an halting linear-time equivalent one. We also obtain polynomial transformations into related models, including weight-reducing Hennie machines, and we show exponential gaps for converse transformations in the deterministic case