theorem Th27: :: FINSEQ_7:27

for D being non empty set
for f being FinSequence of D
for i, j being Nat st 1 <= i & i < j & j <= len f holds
Swap (f,i,j) = ((((f | (i -' 1)) ^ <*(f /. j)*>) ^ ((f /^ i) | ((j -' i) -' 1))) ^ <*(f /. i)*>) ^ (f /^ j)