Theorem resabs1 6024

Description: Absorption law for restriction. Exercise 17 of [TakeutiZaring] p. 25. (Contributed by NM, 9-Aug-1994.)

Assertion

Ref	Expression
resabs1	⊢ (𝐵 ⊆ 𝐶 → ((𝐴 ↾ 𝐶) ↾ 𝐵) = (𝐴 ↾ 𝐵))

Proof of Theorem resabs1

Step	Hyp	Ref	Expression
1		resres 6010	. 2 ⊢ ((𝐴 ↾ 𝐶) ↾ 𝐵) = (𝐴 ↾ (𝐶 ∩ 𝐵))
2		sseqin2 4223	. . 3 ⊢ (𝐵 ⊆ 𝐶 ↔ (𝐶 ∩ 𝐵) = 𝐵)
3		reseq2 5992	. . 3 ⊢ ((𝐶 ∩ 𝐵) = 𝐵 → (𝐴 ↾ (𝐶 ∩ 𝐵)) = (𝐴 ↾ 𝐵))
4	2, 3	sylbi 217	. 2 ⊢ (𝐵 ⊆ 𝐶 → (𝐴 ↾ (𝐶 ∩ 𝐵)) = (𝐴 ↾ 𝐵))
5	1, 4	eqtrid 2789	1 ⊢ (𝐵 ⊆ 𝐶 → ((𝐴 ↾ 𝐶) ↾ 𝐵) = (𝐴 ↾ 𝐵))

Syntax hints:   → wi 4   = wceq 1540   ∩ cin 3950   ⊆ wss 3951   ↾ cres 5687

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1795  ax-4 1809  ax-5 1910  ax-6 1967  ax-7 2007  ax-8 2110  ax-9 2118  ax-ext 2708  ax-sep 5296  ax-nul 5306  ax-pr 5432

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 849  df-3an 1089  df-tru 1543  df-fal 1553  df-ex 1780  df-sb 2065  df-clab 2715  df-cleq 2729  df-clel 2816  df-ral 3062  df-rex 3071  df-rab 3437  df-v 3482  df-dif 3954  df-un 3956  df-in 3958  df-ss 3968  df-nul 4334  df-if 4526  df-sn 4627  df-pr 4629  df-op 4633  df-opab 5206  df-xp 5691  df-rel 5692  df-res 5697

This theorem is referenced by:  resabs1i  6025  resabs1d  6026  resabs2  6027  resiima  6094  fun2ssres  6611  fssres2  6776  smores3  8393  setsres  17215  gsum2dlem2  19989  lindsss  21844  resthauslem  23371  ptcmpfi  23821  tsmsres  24152  ressxms  24538  nrginvrcn  24713  xrge0gsumle  24855  lebnumii  24998  dvmptresicc  25951  dfrelog  26607  relogf1o  26608  dvlog  26693  dvlog2  26695  efopnlem2  26699  wilthlem2  27112  nosupres  27752  nosupbnd2lem1  27760  noinfres  27767  noinfbnd2lem1  27775  nosupinfsep  27777  gsumle  33101  rrhre  34022  iwrdsplit  34389  rpsqrtcn  34608  pthhashvtx  35133  cvmsss2  35279  mbfposadd  37674  mzpcompact2lem  42762  eldioph2  42773  diophin  42783  diophrex  42786  2rexfrabdioph  42807  3rexfrabdioph  42808  4rexfrabdioph  42809  6rexfrabdioph  42810  7rexfrabdioph  42811  fourierdlem46  46167  fourierdlem57  46178  fourierdlem111  46232  fouriersw  46246  psmeasurelem  46485