منابع مشابه
Half-turns and Line Symmetric Motions
A line symmetric motion is the motion obtained by reflecting a rigid body in the successive generator lines of a ruled surface. In this work we review the dual quaternion approach to rigid body displacements, in particular the representation of the group SE(3) by the Study quadric. Then some classical work on reflections in lines or half-turns is reviewed. Next two new characterisations of line...
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Since Å xi for binary variables, aiiÅ 0 could be assumed without any loss of generality. 2 x i It is well known that finding the minimum of f is an NP-hard problem (Garey and Johnson 1979); it contains, as special cases, the vertex cover, maximum cut, signed-graph balancing and MAX-2SAT problems. Moreover, for the general minimization problem there exists a constant c ú 0 such that the existenc...
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We introduce a class of pseudo-Boolean functions called ordered, symmetric half-products. The class includes a number of well known scheduling problems. We study sets of dominating solutions for minimization of the half-products, and we show their fully polynomial time approximation schemes that use a natural rounding scheme to obtain 2-solutions in O(n/2) time.
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The following review covers the primary literature concerning marine natural products isolated for the first time from organisms collected around the islands of Hawaii published in the 51-year period 1964 to July 2015. The review is divided into seven main sections based on major taxonomic groupings; algae, sponges, mollusks, miscellaneous invertebrates, cyanobacteria, bacteria, and fungi. The ...
متن کاملPositive half-products and scheduling with controllable processing times
We study the single machine scheduling problem with controllable job processing times to minimize a linear combination of the total weighted job completion time and the total weighted processing time compression. We show that this scheduling problem is a positive half-product minimization problem. Positive half-products make up an interesting subclass of half-products and are introduced in this...
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ژورنال
عنوان ژورنال: Journal of Algebra
سال: 1986
ISSN: 0021-8693
DOI: 10.1016/0021-8693(86)90026-8