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Theorem sselOLD 3911
 Description: Obsolete version of ssel 3910 as of 27-May-2024. (Contributed by NM, 5-Aug-1993.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
sselOLD (𝐴𝐵 → (𝐶𝐴𝐶𝐵))

Proof of Theorem sselOLD
Dummy variable 𝑥 is distinct from all other variables.
StepHypRef Expression
1 dfss2 3903 . . . . . 6 (𝐴𝐵 ↔ ∀𝑥(𝑥𝐴𝑥𝐵))
21biimpi 219 . . . . 5 (𝐴𝐵 → ∀𝑥(𝑥𝐴𝑥𝐵))
3219.21bi 2186 . . . 4 (𝐴𝐵 → (𝑥𝐴𝑥𝐵))
43anim2d 614 . . 3 (𝐴𝐵 → ((𝑥 = 𝐶𝑥𝐴) → (𝑥 = 𝐶𝑥𝐵)))
54eximdv 1918 . 2 (𝐴𝐵 → (∃𝑥(𝑥 = 𝐶𝑥𝐴) → ∃𝑥(𝑥 = 𝐶𝑥𝐵)))
6 dfclel 2871 . 2 (𝐶𝐴 ↔ ∃𝑥(𝑥 = 𝐶𝑥𝐴))
7 dfclel 2871 . 2 (𝐶𝐵 ↔ ∃𝑥(𝑥 = 𝐶𝑥𝐵))
85, 6, 73imtr4g 299 1 (𝐴𝐵 → (𝐶𝐴𝐶𝐵))
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ∧ wa 399  ∀wal 1536   = wceq 1538  ∃wex 1781   ∈ wcel 2111   ⊆ wss 3883 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1911  ax-6 1970  ax-7 2015  ax-8 2113  ax-9 2121  ax-12 2175  ax-ext 2770 This theorem depends on definitions:  df-bi 210  df-an 400  df-ex 1782  df-sb 2070  df-clab 2777  df-cleq 2791  df-clel 2870  df-v 3444  df-in 3890  df-ss 3900 This theorem is referenced by: (None)
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