منابع مشابه
Enumerating Homomorphisms
The homomorphism problem for relational structures is an abstract way of formulating constraint satisfaction problems (CSP) and various problems in database theory. The decision version of the homomorphism problem received a lot of attention in literature; in particular, the way the graph-theoretical structure of the variables and constraints influences the complexity of the problem is intensiv...
متن کاملEnumerating Molecules
This report is a comprehensive review of the field of molecular enumeration from early isomer counting theories to evolutionary algorithms that design molecules in silico. The core of the review is a detail account on how molecules are counted, enumerated, and sampled. The practical applications of molecular enumeration are also reviewed for chemical information, structure elucidation, molecula...
متن کاملEnumerating Alternating Trees
In this paper we examine the enumeration of alternating trees. We give a bijective proof of the fact that the number of alternating unrooted trees with n vertices is given by 1 n2 n?1 P n k=1 ? n k k n?1 , a problem rst posed by Postnikov in 4]. We also prove, using formal arguments, that the number of alternating plane trees with n vertices is 2(n ? 1) n?1 .
متن کاملEnumerating Perfect Forms
A positive definite quadratic form is called perfect, if it is uniquely determined by its arithmetical minimum and the integral vectors attaining it. In this self-contained survey we explain how to enumerate perfect forms in d variables up to arithmetical equivalence and scaling. We put an emphasis on practical issues concerning computer assisted enumerations. For the necessary theory of Vorono...
متن کاملEnumerating Distinct Decision Trees
The search space for the feature selection problem in decision tree learning is the lattice of subsets of the available features. We provide an exact enumeration procedure of the subsets that lead to all and only the distinct decision trees. The procedure can be adopted to prune the search space of complete and heuristics search methods in wrapper models for feature selection. Based on this, we...
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ژورنال
عنوان ژورنال: Science
سال: 1992
ISSN: 0036-8075,1095-9203
DOI: 10.1126/science.255.5040.92