Theorem add12i 8189

Description: Commutative/associative law that swaps the first two terms in a triple sum. (Contributed by NM, 21-Jan-1997.)

Hypotheses

Ref	Expression
add.1	|- A e. CC
add.2	|- B e. CC
add.3	|- C e. CC

Assertion

Ref	Expression
add12i	|- ( A + ( B + C ) ) = ( B + ( A + C ) )

Proof of Theorem add12i

Step	Hyp	Ref	Expression
1		add.1	. 2 |- A e. CC
2		add.2	. 2 |- B e. CC
3		add.3	. 2 |- C e. CC
4		add12 8184	. 2 |- ( ( A e. CC /\ B e. CC /\ C e. CC ) -> ( A + ( B + C ) ) = ( B + ( A + C ) ) )
5	1, 2, 3, 4	mp3an 1348	1 |- ( A + ( B + C ) ) = ( B + ( A + C ) )

Syntax hints:   = wceq 1364   e. wcel 2167  (class class class)co 5922   CCcc 7877   + caddc 7882

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-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-ext 2178  ax-addcom 7979  ax-addass 7981

This theorem depends on definitions:  df-bi 117  df-3an 982  df-tru 1367  df-nf 1475  df-sb 1777  df-clab 2183  df-cleq 2189  df-clel 2192  df-nfc 2328  df-rex 2481  df-v 2765  df-un 3161  df-sn 3628  df-pr 3629  df-op 3631  df-uni 3840  df-br 4034  df-iota 5219  df-fv 5266  df-ov 5925

This theorem is referenced by: (None)