An inversion in σ ∈ Sn is a pair (i, j) such that i
< j and σ(i) > σ(j). Take σ, τ ∈ Sn and take i
< j.
- Suppose (i, j) is not an inversion in τ. Show that (i, j) is
an inversion in στ if and only if (τ(i), τ(j)) is an inversion in
σ.
- Suppose (i, j) is an inversion in τ. Show that (i, j) is an
inversion in στ if and...