let n be Ordinal; :: thesis: for L being non empty right_complementable Abelian add-associative right_zeroed associative distributive doubleLoopStr
for p, q, r being Series of n,L holds (p + q) *' r = (p *' r) + (q *' r)

let L be non empty right_complementable Abelian add-associative right_zeroed associative distributive doubleLoopStr ; :: thesis: for p, q, r being Series of n,L holds (p + q) *' r = (p *' r) + (q *' r)
let p, q, r be Series of n,L; :: thesis: (p + q) *' r = (p *' r) + (q *' r)
set cL = the carrier of L;
now
let b be Element of Bags n; :: thesis: ((p + q) *' r) . b = ((p *' r) + (q *' r)) . b
consider s being FinSequence of the carrier of L such that
A1: ((p + q) *' r) . b = Sum s and
A2: len s = len (decomp b) and
A3: for k being Element of NAT st k in dom s holds
ex b1, b2 being bag of st
( (decomp b) /. k = <*b1,b2*> & s /. k = ((p + q) . b1) * (r . b2) ) by POLYNOM1:def 26;
consider t being FinSequence of the carrier of L such that
A4: (p *' r) . b = Sum t and
A5: len t = len (decomp b) and
A6: for k being Element of NAT st k in dom t holds
ex b1, b2 being bag of st
( (decomp b) /. k = <*b1,b2*> & t /. k = (p . b1) * (r . b2) ) by POLYNOM1:def 26;
consider u being FinSequence of the carrier of L such that
A7: (q *' r) . b = Sum u and
A8: len u = len (decomp b) and
A9: for k being Element of NAT st k in dom u holds
ex b1, b2 being bag of st
( (decomp b) /. k = <*b1,b2*> & u /. k = (q . b1) * (r . b2) ) by POLYNOM1:def 26;
reconsider S = s, t = t, u = u as Element of (len s) -tuples_on the carrier of L by A2, A5, A8, FINSEQ_2:110;
A10: ( dom t = dom s & dom u = dom s ) by A2, A5, A8, FINSEQ_3:31;
then A11: dom (t + u) = dom s by POLYNOM1:5;
then A12: len (t + u) = len s by FINSEQ_3:31;
X: dom s = Seg (len S) by FINSEQ_1:def 3;
now
let i be Nat; :: thesis: ( i in dom s implies s . i = (t + u) . i )
assume i in dom s ; :: thesis: s . i = (t + u) . i
then ( 1 <= i & i <= len s ) by X, FINSEQ_1:3;
then A13: i in dom s by FINSEQ_3:27;
then consider sb1, sb2 being bag of such that
A14: ( (decomp b) /. i = <*sb1,sb2*> & s /. i = ((p + q) . sb1) * (r . sb2) ) by A3;
consider tb1, tb2 being bag of such that
A15: ( (decomp b) /. i = <*tb1,tb2*> & t /. i = (p . tb1) * (r . tb2) ) by A6, A10, A13;
consider ub1, ub2 being bag of such that
A16: ( (decomp b) /. i = <*ub1,ub2*> & u /. i = (q . ub1) * (r . ub2) ) by A9, A10, A13;
A17: ( sb1 = tb1 & sb1 = ub1 & sb2 = tb2 & sb2 = ub2 ) by A14, A15, A16, GROUP_7:2;
A18: ( s /. i = s . i & t /. i = t . i & u /. i = u . i ) by A10, A13, PARTFUN1:def 8;
hence s . i = ((p . sb1) + (q . sb1)) * (r . sb2) by A14, POLYNOM1:def 21
.= ((p . sb1) * (r . sb2)) + ((q . sb1) * (r . sb2)) by VECTSP_1:def 18
.= (t + u) . i by A11, A13, A15, A16, A17, A18, FVSUM_1:21 ;
:: thesis: verum
end;
then s = t + u by A12, FINSEQ_2:10;
hence ((p + q) *' r) . b = (Sum t) + (Sum u) by A1, FVSUM_1:95
.= ((p *' r) + (q *' r)) . b by A4, A7, POLYNOM1:def 21 ;
:: thesis: verum
end;
hence (p + q) *' r = (p *' r) + (q *' r) by FUNCT_2:113; :: thesis: verum