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Exact Hitting Set
In the mathematical field of combinatorics, given a collection \mathcal of subsets of a set X, an exact cover is a subcollection \mathcal^ of \mathcal such that each element in X is contained in ''exactly one'' subset in \mathcal^. One says that each element in X ''is covered by'' exactly one subset in \mathcal^. An exact cover is a kind of cover. In other words, \mathcal^ is a partition of X consisting of subsets contained in \mathcal. The exact cover problem to find an exact cover is a kind of constraint satisfaction problem. The elements of \mathcal represent choices and the elements of X represent constraints. It is non-deterministic polynomial time (NP) complete and has a variety of applications, ranging from the optimization of airline flight schedules, cloud computing, and electronic circuit design. An exact cover problem involves the relation ''contains'' between subsets and elements. But an exact cover problem can be represented by any heterogeneous relation between a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mathematical
Mathematics is a field of study that discovers and organizes methods, Mathematical theory, theories and theorems that are developed and Mathematical proof, proved for the needs of empirical sciences and mathematics itself. There are many areas of mathematics, which include number theory (the study of numbers), algebra (the study of formulas and related structures), geometry (the study of shapes and spaces that contain them), Mathematical analysis, analysis (the study of continuous changes), and set theory (presently used as a foundation for all mathematics). Mathematics involves the description and manipulation of mathematical object, abstract objects that consist of either abstraction (mathematics), abstractions from nature orin modern mathematicspurely abstract entities that are stipulated to have certain properties, called axioms. Mathematics uses pure reason to proof (mathematics), prove properties of objects, a ''proof'' consisting of a succession of applications of in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A Guide To The Theory Of NP-Completeness
A, or a, is the first letter and the first vowel letter of the Latin alphabet, used in the modern English alphabet, and others worldwide. Its name in English is '' a'' (pronounced ), plural ''aes''. It is similar in shape to the Ancient Greek letter alpha, from which it derives. The uppercase version consists of the two slanting sides of a triangle, crossed in the middle by a horizontal bar. The lowercase version is often written in one of two forms: the double-storey and single-storey . The latter is commonly used in handwriting and fonts based on it, especially fonts intended to be read by children, and is also found in italic type. In English, '' a'' is the indefinite article, with the alternative form ''an''. Name In English, the name of the letter is the ''long A'' sound, pronounced . Its name in most other languages matches the letter's pronunciation in open syllables. History The earliest known ancestor of A is ''aleph''—the first letter of the Phoenician ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
