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Theorem xaddass 10065
Description: Associativity of extended real addition. The correct condition here is "it is not the case that both +oo and -oo appear as one of  A ,  B ,  C, i.e.  -.  { +oo , -oo }  C_  { A ,  B ,  C }", but this condition is difficult to work with, so we break the theorem into two parts: this one, where -oo is not present in  A ,  B ,  C, and xaddass2 10066, where +oo is not present. (Contributed by Mario Carneiro, 20-Aug-2015.)
Assertion
Ref Expression
xaddass  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  ( ( A +e B ) +e C )  =  ( A +e ( B +e C ) ) )

Proof of Theorem xaddass
StepHypRef Expression
1 recn 8132 . . . . . . . . . 10  |-  ( A  e.  RR  ->  A  e.  CC )
2 recn 8132 . . . . . . . . . 10  |-  ( B  e.  RR  ->  B  e.  CC )
3 recn 8132 . . . . . . . . . 10  |-  ( C  e.  RR  ->  C  e.  CC )
4 addass 8129 . . . . . . . . . 10  |-  ( ( A  e.  CC  /\  B  e.  CC  /\  C  e.  CC )  ->  (
( A  +  B
)  +  C )  =  ( A  +  ( B  +  C
) ) )
51, 2, 3, 4syl3an 1313 . . . . . . . . 9  |-  ( ( A  e.  RR  /\  B  e.  RR  /\  C  e.  RR )  ->  (
( A  +  B
)  +  C )  =  ( A  +  ( B  +  C
) ) )
653expa 1227 . . . . . . . 8  |-  ( ( ( A  e.  RR  /\  B  e.  RR )  /\  C  e.  RR )  ->  ( ( A  +  B )  +  C )  =  ( A  +  ( B  +  C ) ) )
7 readdcl 8125 . . . . . . . . 9  |-  ( ( A  e.  RR  /\  B  e.  RR )  ->  ( A  +  B
)  e.  RR )
8 rexadd 10048 . . . . . . . . 9  |-  ( ( ( A  +  B
)  e.  RR  /\  C  e.  RR )  ->  ( ( A  +  B ) +e
C )  =  ( ( A  +  B
)  +  C ) )
97, 8sylan 283 . . . . . . . 8  |-  ( ( ( A  e.  RR  /\  B  e.  RR )  /\  C  e.  RR )  ->  ( ( A  +  B ) +e C )  =  ( ( A  +  B )  +  C
) )
10 readdcl 8125 . . . . . . . . . 10  |-  ( ( B  e.  RR  /\  C  e.  RR )  ->  ( B  +  C
)  e.  RR )
11 rexadd 10048 . . . . . . . . . 10  |-  ( ( A  e.  RR  /\  ( B  +  C
)  e.  RR )  ->  ( A +e ( B  +  C ) )  =  ( A  +  ( B  +  C ) ) )
1210, 11sylan2 286 . . . . . . . . 9  |-  ( ( A  e.  RR  /\  ( B  e.  RR  /\  C  e.  RR ) )  ->  ( A +e ( B  +  C ) )  =  ( A  +  ( B  +  C
) ) )
1312anassrs 400 . . . . . . . 8  |-  ( ( ( A  e.  RR  /\  B  e.  RR )  /\  C  e.  RR )  ->  ( A +e ( B  +  C ) )  =  ( A  +  ( B  +  C ) ) )
146, 9, 133eqtr4d 2272 . . . . . . 7  |-  ( ( ( A  e.  RR  /\  B  e.  RR )  /\  C  e.  RR )  ->  ( ( A  +  B ) +e C )  =  ( A +e
( B  +  C
) ) )
15 rexadd 10048 . . . . . . . . 9  |-  ( ( A  e.  RR  /\  B  e.  RR )  ->  ( A +e
B )  =  ( A  +  B ) )
1615adantr 276 . . . . . . . 8  |-  ( ( ( A  e.  RR  /\  B  e.  RR )  /\  C  e.  RR )  ->  ( A +e B )  =  ( A  +  B
) )
1716oveq1d 6016 . . . . . . 7  |-  ( ( ( A  e.  RR  /\  B  e.  RR )  /\  C  e.  RR )  ->  ( ( A +e B ) +e C )  =  ( ( A  +  B ) +e C ) )
18 rexadd 10048 . . . . . . . . 9  |-  ( ( B  e.  RR  /\  C  e.  RR )  ->  ( B +e
C )  =  ( B  +  C ) )
1918adantll 476 . . . . . . . 8  |-  ( ( ( A  e.  RR  /\  B  e.  RR )  /\  C  e.  RR )  ->  ( B +e C )  =  ( B  +  C
) )
2019oveq2d 6017 . . . . . . 7  |-  ( ( ( A  e.  RR  /\  B  e.  RR )  /\  C  e.  RR )  ->  ( A +e ( B +e C ) )  =  ( A +e ( B  +  C ) ) )
2114, 17, 203eqtr4d 2272 . . . . . 6  |-  ( ( ( A  e.  RR  /\  B  e.  RR )  /\  C  e.  RR )  ->  ( ( A +e B ) +e C )  =  ( A +e ( B +e C ) ) )
2221adantll 476 . . . . 5  |-  ( ( ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  ( A  e.  RR  /\  B  e.  RR ) )  /\  C  e.  RR )  ->  (
( A +e
B ) +e
C )  =  ( A +e ( B +e C ) ) )
23 oveq2 6009 . . . . . . . . 9  |-  ( C  = +oo  ->  (
( A +e
B ) +e
C )  =  ( ( A +e
B ) +e +oo ) )
24 simp1l 1045 . . . . . . . . . . 11  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  A  e.  RR* )
25 simp2l 1047 . . . . . . . . . . 11  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  B  e.  RR* )
26 xaddcl 10056 . . . . . . . . . . 11  |-  ( ( A  e.  RR*  /\  B  e.  RR* )  ->  ( A +e B )  e.  RR* )
2724, 25, 26syl2anc 411 . . . . . . . . . 10  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  ( A +e B )  e.  RR* )
28 xaddnemnf 10053 . . . . . . . . . . 11  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )
)  ->  ( A +e B )  =/= -oo )
29283adant3 1041 . . . . . . . . . 10  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  ( A +e B )  =/= -oo )
30 xaddpnf1 10042 . . . . . . . . . 10  |-  ( ( ( A +e
B )  e.  RR*  /\  ( A +e
B )  =/= -oo )  ->  ( ( A +e B ) +e +oo )  = +oo )
3127, 29, 30syl2anc 411 . . . . . . . . 9  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  ( ( A +e B ) +e +oo )  = +oo )
3223, 31sylan9eqr 2284 . . . . . . . 8  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  C  = +oo )  ->  ( ( A +e B ) +e C )  = +oo )
33 xaddpnf1 10042 . . . . . . . . . 10  |-  ( ( A  e.  RR*  /\  A  =/= -oo )  ->  ( A +e +oo )  = +oo )
34333ad2ant1 1042 . . . . . . . . 9  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  ( A +e +oo )  = +oo )
3534adantr 276 . . . . . . . 8  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  C  = +oo )  ->  ( A +e +oo )  = +oo )
3632, 35eqtr4d 2265 . . . . . . 7  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  C  = +oo )  ->  ( ( A +e B ) +e C )  =  ( A +e +oo ) )
37 oveq2 6009 . . . . . . . . 9  |-  ( C  = +oo  ->  ( B +e C )  =  ( B +e +oo ) )
38 xaddpnf1 10042 . . . . . . . . . 10  |-  ( ( B  e.  RR*  /\  B  =/= -oo )  ->  ( B +e +oo )  = +oo )
39383ad2ant2 1043 . . . . . . . . 9  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  ( B +e +oo )  = +oo )
4037, 39sylan9eqr 2284 . . . . . . . 8  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  C  = +oo )  ->  ( B +e
C )  = +oo )
4140oveq2d 6017 . . . . . . 7  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  C  = +oo )  ->  ( A +e
( B +e
C ) )  =  ( A +e +oo ) )
4236, 41eqtr4d 2265 . . . . . 6  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  C  = +oo )  ->  ( ( A +e B ) +e C )  =  ( A +e
( B +e
C ) ) )
4342adantlr 477 . . . . 5  |-  ( ( ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  ( A  e.  RR  /\  B  e.  RR ) )  /\  C  = +oo )  ->  (
( A +e
B ) +e
C )  =  ( A +e ( B +e C ) ) )
44 simp3 1023 . . . . . . 7  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  ( C  e.  RR*  /\  C  =/= -oo ) )
45 xrnemnf 9973 . . . . . . 7  |-  ( ( C  e.  RR*  /\  C  =/= -oo )  <->  ( C  e.  RR  \/  C  = +oo ) )
4644, 45sylib 122 . . . . . 6  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  ( C  e.  RR  \/  C  = +oo ) )
4746adantr 276 . . . . 5  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  ( A  e.  RR  /\  B  e.  RR ) )  ->  ( C  e.  RR  \/  C  = +oo ) )
4822, 43, 47mpjaodan 803 . . . 4  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  ( A  e.  RR  /\  B  e.  RR ) )  ->  ( ( A +e B ) +e C )  =  ( A +e ( B +e C ) ) )
4948anassrs 400 . . 3  |-  ( ( ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  e.  RR )  /\  B  e.  RR )  ->  ( ( A +e B ) +e C )  =  ( A +e ( B +e C ) ) )
50 xaddpnf2 10043 . . . . . . . 8  |-  ( ( C  e.  RR*  /\  C  =/= -oo )  ->  ( +oo +e C )  = +oo )
51503ad2ant3 1044 . . . . . . 7  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  ( +oo +e C )  = +oo )
5251, 34eqtr4d 2265 . . . . . 6  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  ( +oo +e C )  =  ( A +e +oo ) )
5352adantr 276 . . . . 5  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  B  = +oo )  ->  ( +oo +e
C )  =  ( A +e +oo ) )
54 oveq2 6009 . . . . . . 7  |-  ( B  = +oo  ->  ( A +e B )  =  ( A +e +oo ) )
5554, 34sylan9eqr 2284 . . . . . 6  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  B  = +oo )  ->  ( A +e
B )  = +oo )
5655oveq1d 6016 . . . . 5  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  B  = +oo )  ->  ( ( A +e B ) +e C )  =  ( +oo +e
C ) )
57 oveq1 6008 . . . . . . 7  |-  ( B  = +oo  ->  ( B +e C )  =  ( +oo +e C ) )
5857, 51sylan9eqr 2284 . . . . . 6  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  B  = +oo )  ->  ( B +e
C )  = +oo )
5958oveq2d 6017 . . . . 5  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  B  = +oo )  ->  ( A +e
( B +e
C ) )  =  ( A +e +oo ) )
6053, 56, 593eqtr4d 2272 . . . 4  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  B  = +oo )  ->  ( ( A +e B ) +e C )  =  ( A +e
( B +e
C ) ) )
6160adantlr 477 . . 3  |-  ( ( ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  e.  RR )  /\  B  = +oo )  ->  ( ( A +e B ) +e C )  =  ( A +e ( B +e C ) ) )
62 simpl2 1025 . . . 4  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  e.  RR )  ->  ( B  e.  RR*  /\  B  =/= -oo )
)
63 xrnemnf 9973 . . . 4  |-  ( ( B  e.  RR*  /\  B  =/= -oo )  <->  ( B  e.  RR  \/  B  = +oo ) )
6462, 63sylib 122 . . 3  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  e.  RR )  ->  ( B  e.  RR  \/  B  = +oo ) )
6549, 61, 64mpjaodan 803 . 2  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  e.  RR )  ->  ( ( A +e B ) +e C )  =  ( A +e
( B +e
C ) ) )
66 simpl3 1026 . . . . 5  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  = +oo )  ->  ( C  e.  RR*  /\  C  =/= -oo )
)
6766, 50syl 14 . . . 4  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  = +oo )  ->  ( +oo +e
C )  = +oo )
68 simpl2l 1074 . . . . . 6  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  = +oo )  ->  B  e.  RR* )
69 simpl3l 1076 . . . . . 6  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  = +oo )  ->  C  e.  RR* )
70 xaddcl 10056 . . . . . 6  |-  ( ( B  e.  RR*  /\  C  e.  RR* )  ->  ( B +e C )  e.  RR* )
7168, 69, 70syl2anc 411 . . . . 5  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  = +oo )  ->  ( B +e
C )  e.  RR* )
72 simpl2 1025 . . . . . 6  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  = +oo )  ->  ( B  e.  RR*  /\  B  =/= -oo )
)
73 xaddnemnf 10053 . . . . . 6  |-  ( ( ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  ( B +e C )  =/= -oo )
7472, 66, 73syl2anc 411 . . . . 5  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  = +oo )  ->  ( B +e
C )  =/= -oo )
75 xaddpnf2 10043 . . . . 5  |-  ( ( ( B +e
C )  e.  RR*  /\  ( B +e
C )  =/= -oo )  ->  ( +oo +e ( B +e C ) )  = +oo )
7671, 74, 75syl2anc 411 . . . 4  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  = +oo )  ->  ( +oo +e
( B +e
C ) )  = +oo )
7767, 76eqtr4d 2265 . . 3  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  = +oo )  ->  ( +oo +e
C )  =  ( +oo +e ( B +e C ) ) )
78 simpr 110 . . . . . 6  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  = +oo )  ->  A  = +oo )
7978oveq1d 6016 . . . . 5  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  = +oo )  ->  ( A +e
B )  =  ( +oo +e B ) )
80 xaddpnf2 10043 . . . . . 6  |-  ( ( B  e.  RR*  /\  B  =/= -oo )  ->  ( +oo +e B )  = +oo )
8172, 80syl 14 . . . . 5  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  = +oo )  ->  ( +oo +e
B )  = +oo )
8279, 81eqtrd 2262 . . . 4  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  = +oo )  ->  ( A +e
B )  = +oo )
8382oveq1d 6016 . . 3  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  = +oo )  ->  ( ( A +e B ) +e C )  =  ( +oo +e
C ) )
8478oveq1d 6016 . . 3  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  = +oo )  ->  ( A +e
( B +e
C ) )  =  ( +oo +e
( B +e
C ) ) )
8577, 83, 843eqtr4d 2272 . 2  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  = +oo )  ->  ( ( A +e B ) +e C )  =  ( A +e
( B +e
C ) ) )
86 simp1 1021 . . 3  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  ( A  e.  RR*  /\  A  =/= -oo ) )
87 xrnemnf 9973 . . 3  |-  ( ( A  e.  RR*  /\  A  =/= -oo )  <->  ( A  e.  RR  \/  A  = +oo ) )
8886, 87sylib 122 . 2  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  ( A  e.  RR  \/  A  = +oo ) )
8965, 85, 88mpjaodan 803 1  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  ( ( A +e B ) +e C )  =  ( A +e ( B +e C ) ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    /\ wa 104    \/ wo 713    /\ w3a 1002    = wceq 1395    e. wcel 2200    =/= wne 2400  (class class class)co 6001   CCcc 7997   RRcr 7998    + caddc 8002   +oocpnf 8178   -oocmnf 8179   RR*cxr 8180   +ecxad 9966
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-in1 617  ax-in2 618  ax-io 714  ax-5 1493  ax-7 1494  ax-gen 1495  ax-ie1 1539  ax-ie2 1540  ax-8 1550  ax-10 1551  ax-11 1552  ax-i12 1553  ax-bndl 1555  ax-4 1556  ax-17 1572  ax-i9 1576  ax-ial 1580  ax-i5r 1581  ax-13 2202  ax-14 2203  ax-ext 2211  ax-sep 4202  ax-pow 4258  ax-pr 4293  ax-un 4524  ax-setind 4629  ax-cnex 8090  ax-resscn 8091  ax-1re 8093  ax-addrcl 8096  ax-addass 8101  ax-rnegex 8108
This theorem depends on definitions:  df-bi 117  df-dc 840  df-3or 1003  df-3an 1004  df-tru 1398  df-fal 1401  df-nf 1507  df-sb 1809  df-eu 2080  df-mo 2081  df-clab 2216  df-cleq 2222  df-clel 2225  df-nfc 2361  df-ne 2401  df-nel 2496  df-ral 2513  df-rex 2514  df-rab 2517  df-v 2801  df-sbc 3029  df-csb 3125  df-dif 3199  df-un 3201  df-in 3203  df-ss 3210  df-if 3603  df-pw 3651  df-sn 3672  df-pr 3673  df-op 3675  df-uni 3889  df-iun 3967  df-br 4084  df-opab 4146  df-mpt 4147  df-id 4384  df-xp 4725  df-rel 4726  df-cnv 4727  df-co 4728  df-dm 4729  df-rn 4730  df-res 4731  df-ima 4732  df-iota 5278  df-fun 5320  df-fn 5321  df-f 5322  df-fv 5326  df-ov 6004  df-oprab 6005  df-mpo 6006  df-1st 6286  df-2nd 6287  df-pnf 8183  df-mnf 8184  df-xr 8185  df-xadd 9969
This theorem is referenced by:  xaddass2  10066  xpncan  10067  xadd4d  10081
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