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Heap's algorithm generates all possible permutations of n objects. It was first proposed by B. R. Heap in 1963. [1] The algorithm minimizes movement: it generates each permutation from the previous one by interchanging a single pair of elements; the other n−2 elements are not disturbed. In a 1977 review of permutation-generating algorithms ...
This would have been the first attempt on record to solve a difficult problem in permutations and combinations. [4] Al-Khalil (717–786), an Arab mathematician and cryptographer, wrote the Book of Cryptographic Messages. It contains the first use of permutations and combinations, to list all possible Arabic words with and without vowels. [5]
Combination. In mathematics, a combination is a selection of items from a set that has distinct members, such that the order of selection does not matter (unlike permutations ). For example, given three fruits, say an apple, an orange and a pear, there are three combinations of two that can be drawn from this set: an apple and a pear; an apple ...
A truth table is a structured representation that presents all possible combinations of truth values for the input variables of a Boolean function and their corresponding output values. A function f from A to F is a special relation, a subset of A×F, which simply means that f can be listed as a list of input-output pairs.
All-pairs testing. In computer science, all-pairs testing or pairwise testing is a combinatorial method of software testing that, for each pair of input parameters to a system (typically, a software algorithm ), tests all possible discrete combinations of those parameters. Using carefully chosen test vectors, this can be done much faster than ...
PAPRIKA is based on the fundamental principle that an overall ranking of all possible alternatives representable by a given value model – i.e. all possible combinations of the categories on the criteria – is defined when all pairwise rankings of the alternatives vis-à-vis each other are known (and provided the rankings are consistent).
Generating function. In mathematics, a generating function is a representation of an infinite sequence of numbers as the coefficients of a formal power series. Unlike an ordinary series, the formal power series is not required to converge: in fact, the generating function is not actually regarded as a function, and the "variable" remains an ...
Using tangent half-angle formulas, it follows immediately that α = sin A = 2r / (1 + r2) and β = cos A = (1 − r2) / (1 + r2) are both rational and that α2 + β2 = 1. Multiplying up by the smallest integer that clears the denominators of α and β recovers the original primitive Pythagorean triple.