Theorem eldifad 2923

Description: If a class is in the difference of two classes, it is also in the minuend. One-way deduction form of eldif 2921. (Contributed by David Moews, 1-May-2017.)

Hypothesis

Ref	Expression
eldifad.1	|- (ph -> A e. (B \ C))

Assertion

Ref	Expression
eldifad	|- (ph -> A e. B)

Proof of Theorem eldifad

Step	Hyp	Ref	Expression
1		eldifad.1	. . 3 |- (ph -> A e. (B \ C))
2		eldif 2921	. . 3 |- (A e. (B \ C) <-> (A e. B /\ -. A e. C))
3	1, 2	sylib 127	. 2 |- (ph -> (A e. B /\ -. A e. C))
4	3	simpld 105	1 |- (ph -> A e. B)

Syntax hints:  -. wn 3   -> wi 4   /\ wa 97   e. wcel 1390   \ cdif 2908

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-in1 544  ax-in2 545  ax-io 629  ax-5 1333  ax-7 1334  ax-gen 1335  ax-ie1 1379  ax-ie2 1380  ax-8 1392  ax-10 1393  ax-11 1394  ax-i12 1395  ax-bndl 1396  ax-4 1397  ax-17 1416  ax-i9 1420  ax-ial 1424  ax-i5r 1425  ax-ext 2019

This theorem depends on definitions:  df-bi 110  df-tru 1245  df-nf 1347  df-sb 1643  df-clab 2024  df-cleq 2030  df-clel 2033  df-nfc 2164  df-v 2553  df-dif 2914

This theorem is referenced by: (None)