Consider the permutation sigma what is inv sigma Solutionit

Consider the permutation sigma = what is #inv (sigma)?

Solution

it has ony 2 inversion bcoz l=sigma(l)=4

so only i,j,k will swap with each other.

The pair (1,2) is an inversion of because with i=1 and j=2, we have i<j and (i)=3>1=(j). The remaining inversion is given by the pair (1,3). Thus #inv()=2.