Theorem indif2 3394

Description: Bring an intersection in and out of a class difference. (Contributed by Jeff Hankins, 15-Jul-2009.)

Assertion

Ref	Expression
indif2	|- ( A i^i ( B \ C ) ) = ( ( A i^i B ) \ C )

Proof of Theorem indif2

Step	Hyp	Ref	Expression
1		inass 3360	. 2 |- ( ( A i^i B ) i^i ( _V \ C ) ) = ( A i^i ( B i^i ( _V \ C ) ) )
2		invdif 3392	. 2 |- ( ( A i^i B ) i^i ( _V \ C ) ) = ( ( A i^i B ) \ C )
3		invdif 3392	. . 3 |- ( B i^i ( _V \ C ) ) = ( B \ C )
4	3	ineq2i 3348	. 2 |- ( A i^i ( B i^i ( _V \ C ) ) ) = ( A i^i ( B \ C ) )
5	1, 2, 4	3eqtr3ri 2219	1 |- ( A i^i ( B \ C ) ) = ( ( A i^i B ) \ C )

Syntax hints:   = wceq 1364   _Vcvv 2752   \ cdif 3141   i^i cin 3143

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 1458  ax-7 1459  ax-gen 1460  ax-ie1 1504  ax-ie2 1505  ax-8 1515  ax-10 1516  ax-11 1517  ax-i12 1518  ax-bndl 1520  ax-4 1521  ax-17 1537  ax-i9 1541  ax-ial 1545  ax-i5r 1546  ax-ext 2171

This theorem depends on definitions:  df-bi 117  df-tru 1367  df-nf 1472  df-sb 1774  df-clab 2176  df-cleq 2182  df-clel 2185  df-nfc 2321  df-v 2754  df-dif 3146  df-in 3150

This theorem is referenced by:  indif1  3395  indifcom  3396  difopn  14085