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Sign
Reading time: 1minNota
Working with numbers? See Sign (Arithmetic).
Returns the sign or parity of a permutation. It can be defined as the parity of pairs of elements x,y such that x<y and σ(x)>σ(y). Thus, the sign is +1 is σ is even or -1 if it is odd. Alternatively, the sign of a permutation can be defined from its decomposition into the product of transpositions as , where m is the number of transpositions in the decomposition (although such decomposition is not unique, the parity is an invariant).
Syntax
sign(Permutation)
Description
Given a permutation, returns its sign.