let P be set ; :: thesis: for N being Petri_net of P
for R1, R2, R3 being process of N holds (R1 concur R2) concur R3 = R1 concur (R2 concur R3)

let N be Petri_net of P; :: thesis: for R1, R2, R3 being process of N holds (R1 concur R2) concur R3 = R1 concur (R2 concur R3)
let R1, R2, R3 be process of N; :: thesis: (R1 concur R2) concur R3 = R1 concur (R2 concur R3)
thus (R1 concur R2) concur R3 c= R1 concur (R2 concur R3) :: according to XBOOLE_0:def 10 :: thesis: R1 concur (R2 concur R3) c= (R1 concur R2) concur R3
proof
let x be set ; :: according to TARSKI:def 3 :: thesis: ( not x in (R1 concur R2) concur R3 or x in R1 concur (R2 concur R3) )
assume x in (R1 concur R2) concur R3 ; :: thesis: x in R1 concur (R2 concur R3)
then consider C1 being firing-sequence of N such that
A1: ( x = C1 & ex q1, q2 being FinSubsequence st
( C1 = q1 \/ q2 & q1 misses q2 & Seq q1 in R1 concur R2 & Seq q2 in R3 ) ) ;
consider q1, q2 being FinSubsequence such that
A2: ( C1 = q1 \/ q2 & q1 misses q2 & Seq q1 in R1 concur R2 & Seq q2 in R3 ) by A1;
consider C2 being firing-sequence of N such that
A3: ( Seq q1 = C2 & ex q3, q4 being FinSubsequence st
( C2 = q3 \/ q4 & q3 misses q4 & Seq q3 in R1 & Seq q4 in R2 ) ) by A2;
consider q3, q4 being FinSubsequence such that
A4: ( C2 = q3 \/ q4 & q3 misses q4 & Seq q3 in R1 & Seq q4 in R2 ) by A3;
consider n1 being Nat such that
A5: dom q1 c= Seg n1 by FINSEQ_1:def 12;
A6: ( q3 c= Seq q1 & q4 c= Seq q1 ) by A3, A4, XBOOLE_1:7;
Sgm (dom q1) is one-to-one by A5, FINSEQ_3:99;
then A7: (Sgm (dom q1)) .: (dom q3) misses (Sgm (dom q1)) .: (dom q4) by A4, A6, Th10, FUNCT_1:125;
A8: ( rng ((Sgm (dom q1)) | (dom q3)) = (Sgm (dom q1)) .: (dom q3) & rng ((Sgm (dom q1)) | (dom q4)) = (Sgm (dom q1)) .: (dom q4) ) by RELAT_1:148;
then A9: q1 | (rng ((Sgm (dom q1)) | (dom q3))) misses q1 | (rng ((Sgm (dom q1)) | (dom q4))) by A7, Th9;
A10: dom (Sgm (dom q1)) = dom (q3 \/ q4) by A3, A4, Lm4
.= (dom q3) \/ (dom q4) by RELAT_1:13 ;
A11: (q1 | (rng ((Sgm (dom q1)) | (dom q3)))) \/ (q1 | (rng ((Sgm (dom q1)) | (dom q4)))) = q1 | ((rng ((Sgm (dom q1)) | (dom q3))) \/ (rng ((Sgm (dom q1)) | (dom q4)))) by RELAT_1:107
.= q1 | ((Sgm (dom q1)) .: ((dom q3) \/ (dom q4))) by A8, RELAT_1:153
.= q1 | (rng ((Sgm (dom q1)) | (dom (Sgm (dom q1))))) by A10, RELAT_1:148
.= q1 | (rng (Sgm (dom q1))) by RELAT_1:98
.= q1 | (dom q1) by FINSEQ_1:71
.= q1 by RELAT_1:98 ;
A12: ( dom (q1 | (rng ((Sgm (dom q1)) | (dom q3)))) c= rng ((Sgm (dom q1)) | (dom q3)) & dom (q1 | (rng ((Sgm (dom q1)) | (dom q4)))) c= rng ((Sgm (dom q1)) | (dom q4)) ) by RELAT_1:87;
( rng ((Sgm (dom q1)) | (dom q3)) c= rng (Sgm (dom q1)) & rng ((Sgm (dom q1)) | (dom q4)) c= rng (Sgm (dom q1)) ) by RELAT_1:99;
then ( rng ((Sgm (dom q1)) | (dom q3)) c= dom q1 & rng ((Sgm (dom q1)) | (dom q4)) c= dom q1 ) by FINSEQ_1:71;
then ( dom (q1 | (rng ((Sgm (dom q1)) | (dom q3)))) c= dom q1 & dom (q1 | (rng ((Sgm (dom q1)) | (dom q4)))) c= dom q1 ) by A12, XBOOLE_1:1;
then A13: ( dom (q1 | (rng ((Sgm (dom q1)) | (dom q3)))) c= Seg n1 & dom (q1 | (rng ((Sgm (dom q1)) | (dom q4)))) c= Seg n1 ) by A5, XBOOLE_1:1;
A14: q1 c= C1 by A2, XBOOLE_1:7;
A15: q1 | (rng ((Sgm (dom q1)) | (dom q3))) c= q1 by A11, XBOOLE_1:7;
A16: q1 | (rng ((Sgm (dom q1)) | (dom q4))) c= q1 by A11, XBOOLE_1:7;
rng C1 = (rng q1) \/ (rng q2) by A2, RELAT_1:26;
then A17: rng q1 c= rng C1 by XBOOLE_1:7;
A18: rng q1 = rng (Seq q1) by Lm5;
A19: rng (Seq q1) c= rng C1 by A17, Lm5;
A20: rng (Seq q1) = (rng q3) \/ (rng q4) by A3, A4, RELAT_1:26;
then A21: rng q3 c= rng (Seq q1) by XBOOLE_1:7;
rng q3 = rng (Seq q3) by Lm5;
then A22: rng (Seq q3) c= rng C1 by A19, A21, XBOOLE_1:1;
A23: rng q4 c= rng (Seq q1) by A20, XBOOLE_1:7;
rng q4 = rng (Seq q4) by Lm5;
then A24: rng (Seq q4) c= rng C1 by A19, A23, XBOOLE_1:1;
reconsider q5 = q1 | (rng ((Sgm (dom q1)) | (dom q3))), q6 = q1 | (rng ((Sgm (dom q1)) | (dom q4))) as FinSubsequence by A13, FINSEQ_1:def 12;
reconsider fs = C1 as FinSequence of rng C1 by FINSEQ_1:def 4;
reconsider fs1 = Seq q1 as FinSequence of rng C1 by A17, A18, FINSEQ_1:def 4;
reconsider fs2 = Seq q3 as FinSequence of rng C1 by A22, FINSEQ_1:def 4;
reconsider fs3 = Seq q4 as FinSequence of rng C1 by A24, FINSEQ_1:def 4;
reconsider fss = q1, fss1 = q5, fss2 = q6 as Subset of fs by A14, A15, A16, XBOOLE_1:1;
reconsider fss3 = q3, fss4 = q4 as Subset of fs1 by A3, A4, XBOOLE_1:7;
( Seq fss = fs1 & Seq fss3 = fs2 & fss1 = fss | (rng ((Sgm (dom fss)) | (dom fss3))) ) ;
then A25: Seq q3 = Seq q5 by GRAPH_2:30;
( Seq fss = fs1 & Seq fss4 = fs3 & fss2 = fss | (rng ((Sgm (dom fss)) | (dom fss4))) ) ;
then A26: Seq q4 = Seq q6 by GRAPH_2:30;
q1 /\ q2 = {} by A2, XBOOLE_0:def 7;
then (q5 /\ q2) \/ (q6 /\ q2) = {} by A11, XBOOLE_1:23;
then A27: ( q5 /\ q2 = {} & q6 /\ q2 = {} ) ;
then A28: q6 misses q2 by XBOOLE_0:def 7;
A29: ( q1 c= C1 & q2 c= C1 ) by A2, XBOOLE_1:7;
q6 c= q1 by A11, XBOOLE_1:7;
then q6 c= C1 by A29, XBOOLE_1:1;
then A30: dom q6 misses dom q2 by A28, A29, Th10;
then reconsider q7 = q6 \/ q2 as Function by GRFUNC_1:31;
A31: dom C1 = (dom q1) \/ (dom q2) by A2, RELAT_1:13
.= ((dom q5) \/ (dom q6)) \/ (dom q2) by A11, RELAT_1:13
.= (dom q5) \/ ((dom q6) \/ (dom q2)) by XBOOLE_1:4
.= (dom q5) \/ (dom q7) by RELAT_1:13 ;
then A32: dom q7 c= dom C1 by XBOOLE_1:7;
A33: dom C1 = Seg (len C1) by FINSEQ_1:def 3;
then reconsider q7 = q7 as FinSubsequence by A32, FINSEQ_1:def 12;
A34: C1 = q5 \/ q7 by A2, A11, XBOOLE_1:4;
A35: q5 /\ q7 = (q5 /\ q6) \/ (q5 /\ q2) by XBOOLE_1:23;
q5 /\ q6 = {} by A9, XBOOLE_0:def 7;
then A36: q5 misses q7 by A27, A35, XBOOLE_0:def 7;
A37: rng (Seq q7) = rng q7 by Lm5;
rng C1 = (rng q7) \/ (rng q5) by A34, RELAT_1:26;
then A38: rng (Seq q7) c= rng C1 by A37, XBOOLE_1:7;
rng C1 c= N by FINSEQ_1:def 4;
then rng (Seq q7) c= N by A38, XBOOLE_1:1;
then Seq q7 is FinSequence of N by FINSEQ_1:def 4;
then reconsider C3 = Seq q7 as firing-sequence of N by FINSEQ_1:def 11;
A39: dom (Seq q7) = Seg (len (Seq q7)) by FINSEQ_1:def 3;
( dom (q6 * (Sgm (dom q7))) c= dom (Sgm (dom q7)) & dom (q2 * (Sgm (dom q7))) c= dom (Sgm (dom q7)) ) by RELAT_1:44;
then ( dom (q6 * (Sgm (dom q7))) c= dom (Seq q7) & dom (q2 * (Sgm (dom q7))) c= dom (Seq q7) ) by Lm4;
then reconsider q8 = q6 * (Sgm (dom q7)), q9 = q2 * (Sgm (dom q7)) as FinSubsequence by A39, FINSEQ_1:def 12;
ex ss1, ss2 being FinSubsequence st
( C3 = ss1 \/ ss2 & ss1 misses ss2 & Seq ss1 in R2 & Seq ss2 in R3 )
proof
A40: C3 = q7 * (Sgm (dom q7)) by FINSEQ_1:def 14
.= q8 \/ q9 by RELAT_1:51 ;
A41: dom q8 = (Sgm (dom q7)) " (dom q6) by RELAT_1:182;
A42: dom q9 = (Sgm (dom q7)) " (dom q2) by RELAT_1:182;
(dom q2) /\ (dom q6) = {} by A30, XBOOLE_0:def 7;
then (Sgm (dom q7)) " ((dom q6) /\ (dom q2)) = {} by RELAT_1:171;
then ((Sgm (dom q7)) " (dom q6)) /\ ((Sgm (dom q7)) " (dom q2)) = {} by FUNCT_1:137;
then A43: (Sgm (dom q7)) " (dom q6) misses (Sgm (dom q7)) " (dom q2) by XBOOLE_0:def 7;
( dom q6 c= (dom q6) \/ (dom q2) & dom q2 c= (dom q6) \/ (dom q2) ) by XBOOLE_1:7;
then ( dom q6 c= dom q7 & dom q2 c= dom q7 ) by RELAT_1:13;
then A44: ( dom q6 c= rng (Sgm (dom q7)) & dom q2 c= rng (Sgm (dom q7)) ) by FINSEQ_1:71;
A45: ( dom q8 = (Sgm (dom q7)) " (dom q6) & dom q9 = (Sgm (dom q7)) " (dom q2) ) by RELAT_1:182;
then A46: rng ((Sgm (dom q7)) | (dom q8)) = rng ((dom q6) | (Sgm (dom q7))) by Th12
.= dom q6 by A44, RELAT_1:120 ;
A47: ( dom q8 c= dom (Sgm (dom q7)) & dom q9 c= dom (Sgm (dom q7)) ) by RELAT_1:44;
then A48: (Sgm (dom q7)) * (Sgm (dom q8)) = Sgm (rng ((Sgm (dom q7)) | (dom q8))) by A31, A33, GRAPH_2:3, XBOOLE_1:7;
A49: Seq q8 = (q6 * (Sgm (dom q7))) * (Sgm (dom q8)) by FINSEQ_1:def 14
.= q6 * ((Sgm (dom q7)) * (Sgm (dom q8))) by RELAT_1:55
.= Seq q6 by A46, A48, FINSEQ_1:def 14 ;
A50: rng ((Sgm (dom q7)) | (dom q9)) = rng ((dom q2) | (Sgm (dom q7))) by A45, Th12
.= dom q2 by A44, RELAT_1:120 ;
A51: (Sgm (dom q7)) * (Sgm (dom q9)) = Sgm (rng ((Sgm (dom q7)) | (dom q9))) by A31, A33, A47, GRAPH_2:3, XBOOLE_1:7;
Seq q9 = (q2 * (Sgm (dom q7))) * (Sgm (dom q9)) by FINSEQ_1:def 14
.= q2 * ((Sgm (dom q7)) * (Sgm (dom q9))) by RELAT_1:55
.= Seq q2 by A50, A51, FINSEQ_1:def 14 ;
hence ex ss1, ss2 being FinSubsequence st
( C3 = ss1 \/ ss2 & ss1 misses ss2 & Seq ss1 in R2 & Seq ss2 in R3 ) by A2, A4, A26, A40, A41, A42, A43, A49, Th8; :: thesis: verum
end;
then Seq q7 in R2 concur R3 ;
hence x in R1 concur (R2 concur R3) by A1, A4, A25, A34, A36; :: thesis: verum
end;
let x be set ; :: according to TARSKI:def 3 :: thesis: ( not x in R1 concur (R2 concur R3) or x in (R1 concur R2) concur R3 )
assume x in R1 concur (R2 concur R3) ; :: thesis: x in (R1 concur R2) concur R3
then consider C1 being firing-sequence of N such that
A52: ( x = C1 & ex q1, q2 being FinSubsequence st
( C1 = q1 \/ q2 & q1 misses q2 & Seq q1 in R1 & Seq q2 in R2 concur R3 ) ) ;
consider q1, q2 being FinSubsequence such that
A53: ( C1 = q1 \/ q2 & q1 misses q2 & Seq q1 in R1 & Seq q2 in R2 concur R3 ) by A52;
consider C2 being firing-sequence of N such that
A54: ( Seq q2 = C2 & ex q3, q4 being FinSubsequence st
( C2 = q3 \/ q4 & q3 misses q4 & Seq q3 in R2 & Seq q4 in R3 ) ) by A53;
consider q3, q4 being FinSubsequence such that
A55: ( C2 = q3 \/ q4 & q3 misses q4 & Seq q3 in R2 & Seq q4 in R3 ) by A54;
consider n1 being Nat such that
A56: dom q2 c= Seg n1 by FINSEQ_1:def 12;
A57: ( q3 c= Seq q2 & q4 c= Seq q2 ) by A54, A55, XBOOLE_1:7;
Sgm (dom q2) is one-to-one by A56, FINSEQ_3:99;
then A58: (Sgm (dom q2)) .: (dom q3) misses (Sgm (dom q2)) .: (dom q4) by A55, A57, Th10, FUNCT_1:125;
A59: ( rng ((Sgm (dom q2)) | (dom q3)) = (Sgm (dom q2)) .: (dom q3) & rng ((Sgm (dom q2)) | (dom q4)) = (Sgm (dom q2)) .: (dom q4) ) by RELAT_1:148;
then A60: q2 | (rng ((Sgm (dom q2)) | (dom q3))) misses q2 | (rng ((Sgm (dom q2)) | (dom q4))) by A58, Th9;
A61: dom (Sgm (dom q2)) = dom (Seq q2) by Lm4
.= (dom q3) \/ (dom q4) by A54, A55, RELAT_1:13 ;
A62: (q2 | (rng ((Sgm (dom q2)) | (dom q3)))) \/ (q2 | (rng ((Sgm (dom q2)) | (dom q4)))) = q2 | ((rng ((Sgm (dom q2)) | (dom q3))) \/ (rng ((Sgm (dom q2)) | (dom q4)))) by RELAT_1:107
.= q2 | ((Sgm (dom q2)) .: ((dom q3) \/ (dom q4))) by A59, RELAT_1:153
.= q2 | (rng ((Sgm (dom q2)) | (dom (Sgm (dom q2))))) by A61, RELAT_1:148
.= q2 | (rng (Sgm (dom q2))) by RELAT_1:98
.= q2 | (dom q2) by FINSEQ_1:71
.= q2 by RELAT_1:98 ;
A63: ( dom (q2 | (rng ((Sgm (dom q2)) | (dom q3)))) c= rng ((Sgm (dom q2)) | (dom q3)) & dom (q2 | (rng ((Sgm (dom q2)) | (dom q4)))) c= rng ((Sgm (dom q2)) | (dom q4)) ) by RELAT_1:87;
( rng ((Sgm (dom q2)) | (dom q3)) c= rng (Sgm (dom q2)) & rng ((Sgm (dom q2)) | (dom q4)) c= rng (Sgm (dom q2)) ) by RELAT_1:99;
then ( rng ((Sgm (dom q2)) | (dom q3)) c= dom q2 & rng ((Sgm (dom q2)) | (dom q4)) c= dom q2 ) by FINSEQ_1:71;
then ( dom (q2 | (rng ((Sgm (dom q2)) | (dom q3)))) c= dom q2 & dom (q2 | (rng ((Sgm (dom q2)) | (dom q4)))) c= dom q2 ) by A63, XBOOLE_1:1;
then A64: ( dom (q2 | (rng ((Sgm (dom q2)) | (dom q3)))) c= Seg n1 & dom (q2 | (rng ((Sgm (dom q2)) | (dom q4)))) c= Seg n1 ) by A56, XBOOLE_1:1;
A65: q2 c= C1 by A53, XBOOLE_1:7;
A66: q2 | (rng ((Sgm (dom q2)) | (dom q3))) c= q2 by A62, XBOOLE_1:7;
A67: q2 | (rng ((Sgm (dom q2)) | (dom q4))) c= q2 by A62, XBOOLE_1:7;
rng C1 = (rng q1) \/ (rng q2) by A53, RELAT_1:26;
then A68: rng q2 c= rng C1 by XBOOLE_1:7;
A69: rng q2 = rng (Seq q2) by Lm5;
A70: rng (Seq q2) c= rng C1 by A68, Lm5;
A71: rng (Seq q2) = (rng q3) \/ (rng q4) by A54, A55, RELAT_1:26;
then A72: rng q3 c= rng (Seq q2) by XBOOLE_1:7;
rng q3 = rng (Seq q3) by Lm5;
then A73: rng (Seq q3) c= rng C1 by A70, A72, XBOOLE_1:1;
A74: rng q4 c= rng (Seq q2) by A71, XBOOLE_1:7;
rng q4 = rng (Seq q4) by Lm5;
then A75: rng (Seq q4) c= rng C1 by A70, A74, XBOOLE_1:1;
reconsider q5 = q2 | (rng ((Sgm (dom q2)) | (dom q3))), q6 = q2 | (rng ((Sgm (dom q2)) | (dom q4))) as FinSubsequence by A64, FINSEQ_1:def 12;
reconsider fs = C1 as FinSequence of rng C1 by FINSEQ_1:def 4;
reconsider fs1 = Seq q2 as FinSequence of rng C1 by A68, A69, FINSEQ_1:def 4;
reconsider fs2 = Seq q3 as FinSequence of rng C1 by A73, FINSEQ_1:def 4;
reconsider fs3 = Seq q4 as FinSequence of rng C1 by A75, FINSEQ_1:def 4;
reconsider fss = q2, fss1 = q5, fss2 = q6 as Subset of fs by A65, A66, A67, XBOOLE_1:1;
reconsider fss3 = q3, fss4 = q4 as Subset of fs1 by A54, A55, XBOOLE_1:7;
( Seq fss = fs1 & Seq fss3 = fs2 & fss1 = fss | (rng ((Sgm (dom fss)) | (dom fss3))) ) ;
then A76: Seq q5 in R2 by A55, GRAPH_2:30;
( Seq fss = fs1 & Seq fss4 = fs3 & fss2 = fss | (rng ((Sgm (dom fss)) | (dom fss4))) ) ;
then A77: Seq q4 = Seq q6 by GRAPH_2:30;
q1 /\ q2 = {} by A53, XBOOLE_0:def 7;
then (q1 /\ q5) \/ (q1 /\ q6) = {} by A62, XBOOLE_1:23;
then A78: ( q1 /\ q5 = {} & q1 /\ q6 = {} ) ;
then A79: q1 misses q5 by XBOOLE_0:def 7;
A80: ( q1 c= C1 & q2 c= C1 ) by A53, XBOOLE_1:7;
q5 c= q2 by A62, XBOOLE_1:7;
then q5 c= C1 by A80, XBOOLE_1:1;
then A81: dom q1 misses dom q5 by A79, A80, Th10;
then reconsider q7 = q1 \/ q5 as Function by GRFUNC_1:31;
A82: dom C1 = (dom q1) \/ (dom q2) by A53, RELAT_1:13
.= (dom q1) \/ ((dom q5) \/ (dom q6)) by A62, RELAT_1:13
.= ((dom q1) \/ (dom q5)) \/ (dom q6) by XBOOLE_1:4
.= (dom q7) \/ (dom q6) by RELAT_1:13 ;
then A83: dom q7 c= dom C1 by XBOOLE_1:7;
A84: dom C1 = Seg (len C1) by FINSEQ_1:def 3;
then reconsider q7 = q7 as FinSubsequence by A83, FINSEQ_1:def 12;
A85: C1 = q7 \/ q6 by A53, A62, XBOOLE_1:4;
A86: q7 /\ q6 = (q1 /\ q6) \/ (q5 /\ q6) by XBOOLE_1:23;
q5 /\ q6 = {} by A60, XBOOLE_0:def 7;
then A87: q7 misses q6 by A78, A86, XBOOLE_0:def 7;
A88: rng (Seq q7) = rng q7 by Lm5;
rng C1 = (rng q7) \/ (rng q6) by A85, RELAT_1:26;
then A89: rng (Seq q7) c= rng C1 by A88, XBOOLE_1:7;
rng C1 c= N by FINSEQ_1:def 4;
then rng (Seq q7) c= N by A89, XBOOLE_1:1;
then Seq q7 is FinSequence of N by FINSEQ_1:def 4;
then reconsider C3 = Seq q7 as firing-sequence of N by FINSEQ_1:def 11;
A90: dom (Seq q7) = Seg (len (Seq q7)) by FINSEQ_1:def 3;
( dom (q1 * (Sgm (dom q7))) c= dom (Sgm (dom q7)) & dom (q5 * (Sgm (dom q7))) c= dom (Sgm (dom q7)) ) by RELAT_1:44;
then ( dom (q1 * (Sgm (dom q7))) c= dom (Seq q7) & dom (q5 * (Sgm (dom q7))) c= dom (Seq q7) ) by Lm4;
then reconsider q8 = q1 * (Sgm (dom q7)), q9 = q5 * (Sgm (dom q7)) as FinSubsequence by A90, FINSEQ_1:def 12;
ex ss1, ss2 being FinSubsequence st
( C3 = ss1 \/ ss2 & ss1 misses ss2 & Seq ss1 in R1 & Seq ss2 in R2 )
proof
A91: C3 = q7 * (Sgm (dom q7)) by FINSEQ_1:def 14
.= q8 \/ q9 by RELAT_1:51 ;
A92: dom q8 = (Sgm (dom q7)) " (dom q1) by RELAT_1:182;
A93: dom q9 = (Sgm (dom q7)) " (dom q5) by RELAT_1:182;
(dom q1) /\ (dom q5) = {} by A81, XBOOLE_0:def 7;
then (Sgm (dom q7)) " ((dom q1) /\ (dom q5)) = {} by RELAT_1:171;
then ((Sgm (dom q7)) " (dom q1)) /\ ((Sgm (dom q7)) " (dom q5)) = {} by FUNCT_1:137;
then A94: (Sgm (dom q7)) " (dom q1) misses (Sgm (dom q7)) " (dom q5) by XBOOLE_0:def 7;
( dom q1 c= (dom q1) \/ (dom q5) & dom q5 c= (dom q1) \/ (dom q5) ) by XBOOLE_1:7;
then ( dom q1 c= dom q7 & dom q5 c= dom q7 ) by RELAT_1:13;
then A95: ( dom q1 c= rng (Sgm (dom q7)) & dom q5 c= rng (Sgm (dom q7)) ) by FINSEQ_1:71;
A96: ( dom q8 = (Sgm (dom q7)) " (dom q1) & dom q9 = (Sgm (dom q7)) " (dom q5) ) by RELAT_1:182;
then A97: rng ((Sgm (dom q7)) | (dom q8)) = rng ((dom q1) | (Sgm (dom q7))) by Th12
.= dom q1 by A95, RELAT_1:120 ;
A98: ( dom q8 c= dom (Sgm (dom q7)) & dom q9 c= dom (Sgm (dom q7)) ) by RELAT_1:44;
then A99: (Sgm (dom q7)) * (Sgm (dom q8)) = Sgm (rng ((Sgm (dom q7)) | (dom q8))) by A82, A84, GRAPH_2:3, XBOOLE_1:7;
A100: Seq q8 = (q1 * (Sgm (dom q7))) * (Sgm (dom q8)) by FINSEQ_1:def 14
.= q1 * ((Sgm (dom q7)) * (Sgm (dom q8))) by RELAT_1:55
.= Seq q1 by A97, A99, FINSEQ_1:def 14 ;
A101: rng ((Sgm (dom q7)) | (dom q9)) = rng ((dom q5) | (Sgm (dom q7))) by A96, Th12
.= dom q5 by A95, RELAT_1:120 ;
A102: (Sgm (dom q7)) * (Sgm (dom q9)) = Sgm (rng ((Sgm (dom q7)) | (dom q9))) by A82, A84, A98, GRAPH_2:3, XBOOLE_1:7;
Seq q9 = (q5 * (Sgm (dom q7))) * (Sgm (dom q9)) by FINSEQ_1:def 14
.= q5 * ((Sgm (dom q7)) * (Sgm (dom q9))) by RELAT_1:55
.= Seq q5 by A101, A102, FINSEQ_1:def 14 ;
hence ex ss1, ss2 being FinSubsequence st
( C3 = ss1 \/ ss2 & ss1 misses ss2 & Seq ss1 in R1 & Seq ss2 in R2 ) by A53, A76, A91, A92, A93, A94, A100, Th8; :: thesis: verum
end;
then Seq q7 in R1 concur R2 ;
hence x in (R1 concur R2) concur R3 by A52, A55, A77, A85, A87; :: thesis: verum