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Theorem funresdfunsnss 5635
 Description: Restricting a function to a domain without one element of the domain of the function, and adding a pair of this element and the function value of the element results in a subset of the function itself. (Contributed by AV, 2-Dec-2018.) (Revised by Jim Kingdon, 21-Jan-2023.)
Assertion
Ref Expression
funresdfunsnss ((Fun 𝐹𝑋 ∈ dom 𝐹) → ((𝐹 ↾ (V ∖ {𝑋})) ∪ {⟨𝑋, (𝐹𝑋)⟩}) ⊆ 𝐹)

Proof of Theorem funresdfunsnss
StepHypRef Expression
1 funrel 5152 . . . . 5 (Fun 𝐹 → Rel 𝐹)
2 resdmdfsn 4874 . . . . 5 (Rel 𝐹 → (𝐹 ↾ (V ∖ {𝑋})) = (𝐹 ↾ (dom 𝐹 ∖ {𝑋})))
31, 2syl 14 . . . 4 (Fun 𝐹 → (𝐹 ↾ (V ∖ {𝑋})) = (𝐹 ↾ (dom 𝐹 ∖ {𝑋})))
43adantr 274 . . 3 ((Fun 𝐹𝑋 ∈ dom 𝐹) → (𝐹 ↾ (V ∖ {𝑋})) = (𝐹 ↾ (dom 𝐹 ∖ {𝑋})))
54uneq1d 3236 . 2 ((Fun 𝐹𝑋 ∈ dom 𝐹) → ((𝐹 ↾ (V ∖ {𝑋})) ∪ {⟨𝑋, (𝐹𝑋)⟩}) = ((𝐹 ↾ (dom 𝐹 ∖ {𝑋})) ∪ {⟨𝑋, (𝐹𝑋)⟩}))
6 funfn 5165 . . 3 (Fun 𝐹𝐹 Fn dom 𝐹)
7 fnsnsplitss 5631 . . 3 ((𝐹 Fn dom 𝐹𝑋 ∈ dom 𝐹) → ((𝐹 ↾ (dom 𝐹 ∖ {𝑋})) ∪ {⟨𝑋, (𝐹𝑋)⟩}) ⊆ 𝐹)
86, 7sylanb 282 . 2 ((Fun 𝐹𝑋 ∈ dom 𝐹) → ((𝐹 ↾ (dom 𝐹 ∖ {𝑋})) ∪ {⟨𝑋, (𝐹𝑋)⟩}) ⊆ 𝐹)
95, 8eqsstrd 3140 1 ((Fun 𝐹𝑋 ∈ dom 𝐹) → ((𝐹 ↾ (V ∖ {𝑋})) ∪ {⟨𝑋, (𝐹𝑋)⟩}) ⊆ 𝐹)
 Colors of variables: wff set class Syntax hints:   → wi 4   ∧ wa 103   = wceq 1332   ∈ wcel 2112  Vcvv 2691   ∖ cdif 3075   ∪ cun 3076   ⊆ wss 3078  {csn 3534  ⟨cop 3537  dom cdm 4551   ↾ cres 4553  Rel wrel 4556  Fun wfun 5129   Fn wfn 5130  ‘cfv 5135 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 604  ax-in2 605  ax-io 699  ax-5 1424  ax-7 1425  ax-gen 1426  ax-ie1 1470  ax-ie2 1471  ax-8 1481  ax-10 1482  ax-11 1483  ax-i12 1484  ax-bndl 1486  ax-4 1487  ax-17 1503  ax-i9 1507  ax-ial 1511  ax-i5r 1512  ax-14 2115  ax-ext 2123  ax-sep 4056  ax-pow 4108  ax-pr 4142 This theorem depends on definitions:  df-bi 116  df-3an 965  df-tru 1335  df-nf 1438  df-sb 1732  df-eu 1993  df-mo 1994  df-clab 2128  df-cleq 2134  df-clel 2137  df-nfc 2272  df-ral 2423  df-rex 2424  df-reu 2425  df-rab 2427  df-v 2693  df-sbc 2916  df-dif 3080  df-un 3082  df-in 3084  df-ss 3091  df-pw 3519  df-sn 3540  df-pr 3541  df-op 3543  df-uni 3747  df-br 3940  df-opab 4000  df-id 4226  df-xp 4557  df-rel 4558  df-cnv 4559  df-co 4560  df-dm 4561  df-rn 4562  df-res 4563  df-ima 4564  df-iota 5100  df-fun 5137  df-fn 5138  df-f 5139  df-f1 5140  df-fo 5141  df-f1o 5142  df-fv 5143 This theorem is referenced by: (None)
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