Theorem dmss 4954

Description: Subset theorem for domain. (Contributed by NM, 11-Aug-1994.)

Assertion

Ref	Expression
dmss	⊢ (𝐴 ⊆ 𝐵 → dom 𝐴 ⊆ dom 𝐵)

Proof of Theorem dmss

Dummy variables 𝑥 𝑦 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		ssel 3231	. . . 4 ⊢ (𝐴 ⊆ 𝐵 → (⟨𝑥, 𝑦⟩ ∈ 𝐴 → ⟨𝑥, 𝑦⟩ ∈ 𝐵))
2	1	eximdv 1929	. . 3 ⊢ (𝐴 ⊆ 𝐵 → (∃𝑦⟨𝑥, 𝑦⟩ ∈ 𝐴 → ∃𝑦⟨𝑥, 𝑦⟩ ∈ 𝐵))
3		vex 2815	. . . 4 ⊢ 𝑥 ∈ V
4	3	eldm2 4953	. . 3 ⊢ (𝑥 ∈ dom 𝐴 ↔ ∃𝑦⟨𝑥, 𝑦⟩ ∈ 𝐴)
5	3	eldm2 4953	. . 3 ⊢ (𝑥 ∈ dom 𝐵 ↔ ∃𝑦⟨𝑥, 𝑦⟩ ∈ 𝐵)
6	2, 4, 5	3imtr4g 205	. 2 ⊢ (𝐴 ⊆ 𝐵 → (𝑥 ∈ dom 𝐴 → 𝑥 ∈ dom 𝐵))
7	6	ssrdv 3243	1 ⊢ (𝐴 ⊆ 𝐵 → dom 𝐴 ⊆ dom 𝐵)

Syntax hints:   → wi 4  ∃wex 1541   ∈ wcel 2203   ⊆ wss 3210  ⟨cop 3691  dom cdm 4748

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 717  ax-5 1496  ax-7 1497  ax-gen 1498  ax-ie1 1542  ax-ie2 1543  ax-8 1553  ax-10 1554  ax-11 1555  ax-i12 1556  ax-bndl 1558  ax-4 1559  ax-17 1575  ax-i9 1579  ax-ial 1583  ax-i5r 1584  ax-ext 2214

This theorem depends on definitions:  df-bi 117  df-3an 1007  df-tru 1401  df-nf 1510  df-sb 1812  df-clab 2219  df-cleq 2225  df-clel 2228  df-nfc 2373  df-v 2814  df-un 3214  df-in 3216  df-ss 3223  df-sn 3694  df-pr 3695  df-op 3697  df-br 4109  df-dm 4758

This theorem is referenced by:  dmeq  4955  dmv  4971  rnss  4986  dmiin  5002  dmxpss2  5194  ssxpbm  5197  ssxp1  5198  cocnvres  5286  relrelss  5288  funssxp  5531  fvun1  5742  fndmdif  5782  fneqeql2  5786  funsssuppss  6457  tposss  6476  smores  6522  smores2  6524  tfrlemibfn  6558  tfrlemiubacc  6560  tfr1onlembfn  6574  tfr1onlemubacc  6576  tfr1onlemres  6579  tfrcllembfn  6587  tfrcllemubacc  6589  tfrcllemres  6592  frecuzrdgtcl  10773  frecuzrdgdomlem  10778  hashdmprop2dom  11212  ennnfonelemex  13157  strleund  13308  strleun  13309  imasaddfnlemg  13519  dvbssntrcntop  15541  subgreldmiedg  16256