let i be Nat; :: thesis: for D being non empty set
for p being Element of D
for f being FinSequence of D st p in rng f & 1 <= i & i <= len (f :- p) holds
(Rotate (f,p)) /. i = f /. ((i -' 1) + (p .. f))

let D be non empty set ; :: thesis: for p being Element of D
for f being FinSequence of D st p in rng f & 1 <= i & i <= len (f :- p) holds
(Rotate (f,p)) /. i = f /. ((i -' 1) + (p .. f))

let p be Element of D; :: thesis: for f being FinSequence of D st p in rng f & 1 <= i & i <= len (f :- p) holds
(Rotate (f,p)) /. i = f /. ((i -' 1) + (p .. f))

let f be FinSequence of D; :: thesis: ( p in rng f & 1 <= i & i <= len (f :- p) implies (Rotate (f,p)) /. i = f /. ((i -' 1) + (p .. f)) )
assume that
A1: p in rng f and
A2: 1 <= i and
A3: i <= len (f :- p) ; :: thesis: (Rotate (f,p)) /. i = f /. ((i -' 1) + (p .. f))
A4: i in dom (f :- p) by ;
A5: i = (i -' 1) + 1 by ;
Rotate (f,p) = (f :- p) ^ ((f -: p) /^ 1) by ;
hence (Rotate (f,p)) /. i = (f :- p) /. i by
.= f /. ((i -' 1) + (p .. f)) by ;
:: thesis: verum