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Theorem xaddass 9944
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 9945, 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 8012 . . . . . . . . . 10  |-  ( A  e.  RR  ->  A  e.  CC )
2 recn 8012 . . . . . . . . . 10  |-  ( B  e.  RR  ->  B  e.  CC )
3 recn 8012 . . . . . . . . . 10  |-  ( C  e.  RR  ->  C  e.  CC )
4 addass 8009 . . . . . . . . . 10  |-  ( ( A  e.  CC  /\  B  e.  CC  /\  C  e.  CC )  ->  (
( A  +  B
)  +  C )  =  ( A  +  ( B  +  C
) ) )
51, 2, 3, 4syl3an 1291 . . . . . . . . 9  |-  ( ( A  e.  RR  /\  B  e.  RR  /\  C  e.  RR )  ->  (
( A  +  B
)  +  C )  =  ( A  +  ( B  +  C
) ) )
653expa 1205 . . . . . . . 8  |-  ( ( ( A  e.  RR  /\  B  e.  RR )  /\  C  e.  RR )  ->  ( ( A  +  B )  +  C )  =  ( A  +  ( B  +  C ) ) )
7 readdcl 8005 . . . . . . . . 9  |-  ( ( A  e.  RR  /\  B  e.  RR )  ->  ( A  +  B
)  e.  RR )
8 rexadd 9927 . . . . . . . . 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 8005 . . . . . . . . . 10  |-  ( ( B  e.  RR  /\  C  e.  RR )  ->  ( B  +  C
)  e.  RR )
11 rexadd 9927 . . . . . . . . . 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 2239 . . . . . . 7  |-  ( ( ( A  e.  RR  /\  B  e.  RR )  /\  C  e.  RR )  ->  ( ( A  +  B ) +e C )  =  ( A +e
( B  +  C
) ) )
15 rexadd 9927 . . . . . . . . 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 5937 . . . . . . 7  |-  ( ( ( A  e.  RR  /\  B  e.  RR )  /\  C  e.  RR )  ->  ( ( A +e B ) +e C )  =  ( ( A  +  B ) +e C ) )
18 rexadd 9927 . . . . . . . . 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 5938 . . . . . . 7  |-  ( ( ( A  e.  RR  /\  B  e.  RR )  /\  C  e.  RR )  ->  ( A +e ( B +e C ) )  =  ( A +e ( B  +  C ) ) )
2114, 17, 203eqtr4d 2239 . . . . . 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 5930 . . . . . . . . 9  |-  ( C  = +oo  ->  (
( A +e
B ) +e
C )  =  ( ( A +e
B ) +e +oo ) )
24 simp1l 1023 . . . . . . . . . . 11  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  A  e.  RR* )
25 simp2l 1025 . . . . . . . . . . 11  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  B  e.  RR* )
26 xaddcl 9935 . . . . . . . . . . 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 9932 . . . . . . . . . . 11  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )
)  ->  ( A +e B )  =/= -oo )
29283adant3 1019 . . . . . . . . . 10  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  ( A +e B )  =/= -oo )
30 xaddpnf1 9921 . . . . . . . . . 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 2251 . . . . . . . 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 9921 . . . . . . . . . 10  |-  ( ( A  e.  RR*  /\  A  =/= -oo )  ->  ( A +e +oo )  = +oo )
34333ad2ant1 1020 . . . . . . . . 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 2232 . . . . . . 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 5930 . . . . . . . . 9  |-  ( C  = +oo  ->  ( B +e C )  =  ( B +e +oo ) )
38 xaddpnf1 9921 . . . . . . . . . 10  |-  ( ( B  e.  RR*  /\  B  =/= -oo )  ->  ( B +e +oo )  = +oo )
39383ad2ant2 1021 . . . . . . . . 9  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  ( B +e +oo )  = +oo )
4037, 39sylan9eqr 2251 . . . . . . . 8  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  C  = +oo )  ->  ( B +e
C )  = +oo )
4140oveq2d 5938 . . . . . . 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 2232 . . . . . 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 1001 . . . . . . 7  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  ( C  e.  RR*  /\  C  =/= -oo ) )
45 xrnemnf 9852 . . . . . . 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 799 . . . 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 9922 . . . . . . . 8  |-  ( ( C  e.  RR*  /\  C  =/= -oo )  ->  ( +oo +e C )  = +oo )
51503ad2ant3 1022 . . . . . . 7  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  ( +oo +e C )  = +oo )
5251, 34eqtr4d 2232 . . . . . 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 5930 . . . . . . 7  |-  ( B  = +oo  ->  ( A +e B )  =  ( A +e +oo ) )
5554, 34sylan9eqr 2251 . . . . . 6  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  B  = +oo )  ->  ( A +e
B )  = +oo )
5655oveq1d 5937 . . . . 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 5929 . . . . . . 7  |-  ( B  = +oo  ->  ( B +e C )  =  ( +oo +e C ) )
5857, 51sylan9eqr 2251 . . . . . 6  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  B  = +oo )  ->  ( B +e
C )  = +oo )
5958oveq2d 5938 . . . . 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 2239 . . . 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 1003 . . . 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 9852 . . . 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 799 . 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 1004 . . . . 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 1052 . . . . . 6  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  = +oo )  ->  B  e.  RR* )
69 simpl3l 1054 . . . . . 6  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  = +oo )  ->  C  e.  RR* )
70 xaddcl 9935 . . . . . 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 1003 . . . . . 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 9932 . . . . . 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 9922 . . . . 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 2232 . . 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 5937 . . . . 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 9922 . . . . . 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 2229 . . . 4  |-  ( ( ( ( A  e. 
RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo ) )  /\  A  = +oo )  ->  ( A +e
B )  = +oo )
8382oveq1d 5937 . . 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 5937 . . 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 2239 . 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 999 . . 3  |-  ( ( ( A  e.  RR*  /\  A  =/= -oo )  /\  ( B  e.  RR*  /\  B  =/= -oo )  /\  ( C  e.  RR*  /\  C  =/= -oo )
)  ->  ( A  e.  RR*  /\  A  =/= -oo ) )
87 xrnemnf 9852 . . 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 799 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 709    /\ w3a 980    = wceq 1364    e. wcel 2167    =/= wne 2367  (class class class)co 5922   CCcc 7877   RRcr 7878    + caddc 7882   +oocpnf 8058   -oocmnf 8059   RR*cxr 8060   +ecxad 9845
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 615  ax-in2 616  ax-io 710  ax-5 1461  ax-7 1462  ax-gen 1463  ax-ie1 1507  ax-ie2 1508  ax-8 1518  ax-10 1519  ax-11 1520  ax-i12 1521  ax-bndl 1523  ax-4 1524  ax-17 1540  ax-i9 1544  ax-ial 1548  ax-i5r 1549  ax-13 2169  ax-14 2170  ax-ext 2178  ax-sep 4151  ax-pow 4207  ax-pr 4242  ax-un 4468  ax-setind 4573  ax-cnex 7970  ax-resscn 7971  ax-1re 7973  ax-addrcl 7976  ax-addass 7981  ax-rnegex 7988
This theorem depends on definitions:  df-bi 117  df-dc 836  df-3or 981  df-3an 982  df-tru 1367  df-fal 1370  df-nf 1475  df-sb 1777  df-eu 2048  df-mo 2049  df-clab 2183  df-cleq 2189  df-clel 2192  df-nfc 2328  df-ne 2368  df-nel 2463  df-ral 2480  df-rex 2481  df-rab 2484  df-v 2765  df-sbc 2990  df-csb 3085  df-dif 3159  df-un 3161  df-in 3163  df-ss 3170  df-if 3562  df-pw 3607  df-sn 3628  df-pr 3629  df-op 3631  df-uni 3840  df-iun 3918  df-br 4034  df-opab 4095  df-mpt 4096  df-id 4328  df-xp 4669  df-rel 4670  df-cnv 4671  df-co 4672  df-dm 4673  df-rn 4674  df-res 4675  df-ima 4676  df-iota 5219  df-fun 5260  df-fn 5261  df-f 5262  df-fv 5266  df-ov 5925  df-oprab 5926  df-mpo 5927  df-1st 6198  df-2nd 6199  df-pnf 8063  df-mnf 8064  df-xr 8065  df-xadd 9848
This theorem is referenced by:  xaddass2  9945  xpncan  9946  xadd4d  9960
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