let L be non empty right_complementable add-associative right_zeroed well-unital distributive doubleLoopStr ; :: thesis: for n, x being Element of NAT
for a being Element of L
for p being Polynomial of L holds ((monomial a,n) *' p) . (x + n) = a * (p . x)

let n, x be Element of NAT ; :: thesis: for a being Element of L
for p being Polynomial of L holds ((monomial a,n) *' p) . (x + n) = a * (p . x)

let a be Element of L; :: thesis: for p being Polynomial of L holds ((monomial a,n) *' p) . (x + n) = a * (p . x)
let p be Polynomial of L; :: thesis: ((monomial a,n) *' p) . (x + n) = a * (p . x)
consider r being FinSequence of the carrier of L such that
A1: ( len r = (x + n) + 1 & ((monomial a,n) *' p) . (x + n) = Sum r & ( for k being Element of NAT st k in dom r holds
r . k = ((monomial a,n) . (k -' 1)) * (p . (((x + n) + 1) -' k)) ) ) by POLYNOM3:def 11;
len r = n + (1 + x) by A1;
then consider b, c being FinSequence of the carrier of L such that
A2: ( len b = n & len c = 1 + x & r = b ^ c ) by FINSEQ_2:26;
consider d, e being FinSequence of the carrier of L such that
A3: ( len d = 1 & len e = x & c = d ^ e ) by A2, FINSEQ_2:26;
now
let i be Element of NAT ; :: thesis: ( i in dom b implies b . i = 0. L )
assume A4: i in dom b ; :: thesis: b . i = 0. L
then A5: ( 1 <= i & i <= n ) by A2, FINSEQ_3:27;
then A6: i -' 1 = i - 1 by XREAL_1:235;
A7: i - 1 < i by XREAL_1:148;
A8: dom b c= dom r by A2, FINSEQ_1:39;
thus b . i = r . i by A2, A4, FINSEQ_1:def 7
.= ((monomial a,n) . (i -' 1)) * (p . (((x + n) + 1) -' i)) by A1, A4, A8
.= (0. L) * (p . (((x + n) + 1) -' i)) by A5, A6, A7, Def5
.= 0. L by VECTSP_1:39 ; :: thesis: verum
end;
then A9: Sum b = 0. L by POLYNOM3:1;
A10: 1 in dom d by A3, FINSEQ_3:27;
A11: dom d c= dom c by A3, FINSEQ_1:39;
d . 1 = c . 1 by A3, A10, FINSEQ_1:def 7
.= r . (n + 1) by A2, A10, A11, FINSEQ_1:def 7
.= ((monomial a,n) . ((n + 1) -' 1)) * (p . (((x + n) + 1) -' (n + 1))) by A1, A2, A10, A11, FINSEQ_1:41
.= ((monomial a,n) . n) * (p . ((x + (n + 1)) -' (n + 1))) by NAT_D:34
.= ((monomial a,n) . n) * (p . x) by NAT_D:34
.= a * (p . x) by Def5 ;
then d = <*(a * (p . x))*> by A3, FINSEQ_1:57;
then A12: Sum d = a * (p . x) by RLVECT_1:61;
now
let i be Element of NAT ; :: thesis: ( i in dom e implies e . i = 0. L )
assume A13: i in dom e ; :: thesis: e . i = 0. L
then A14: 1 + i in dom c by A3, FINSEQ_1:41;
i >= 1 by A13, FINSEQ_3:27;
then n + i >= n + 1 by XREAL_1:8;
then A15: n + i > n by NAT_1:13;
A16: (n + (1 + i)) -' 1 = ((n + i) + 1) -' 1
.= n + i by NAT_D:34 ;
thus e . i = c . (1 + i) by A3, A13, FINSEQ_1:def 7
.= r . (n + (1 + i)) by A2, A14, FINSEQ_1:def 7
.= ((monomial a,n) . ((n + (1 + i)) -' 1)) * (p . (((x + n) + 1) -' (n + (1 + i)))) by A1, A2, A14, FINSEQ_1:41
.= (0. L) * (p . (((x + n) + 1) -' (n + (1 + i)))) by A15, A16, Def5
.= 0. L by VECTSP_1:39 ; :: thesis: verum
end;
then Sum e = 0. L by POLYNOM3:1;
then Sum c = (a * (p . x)) + (0. L) by A3, A12, RLVECT_1:58
.= a * (p . x) by RLVECT_1:10 ;
hence ((monomial a,n) *' p) . (x + n) = (0. L) + (a * (p . x)) by A1, A2, A9, RLVECT_1:58
.= a * (p . x) by RLVECT_1:10 ;
:: thesis: verum