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Theorem ss2abim 4008
Description: Class abstractions in a subclass relationship. Reverse direction of ss2ab 4009 which requires fewer axioms. (Contributed by SN, 22-Dec-2024.)
Assertion
Ref Expression
ss2abim (∀𝑥(𝜑𝜓) → {𝑥𝜑} ⊆ {𝑥𝜓})

Proof of Theorem ss2abim
Dummy variable 𝑡 is distinct from all other variables.
StepHypRef Expression
1 spsbim 2099 . . 3 (∀𝑥(𝜑𝜓) → ([𝑡 / 𝑥]𝜑 → [𝑡 / 𝑥]𝜓))
2 df-clab 2735 . . 3 (𝑡 ∈ {𝑥𝜑} ↔ [𝑡 / 𝑥]𝜑)
3 df-clab 2735 . . 3 (𝑡 ∈ {𝑥𝜓} ↔ [𝑡 / 𝑥]𝜓)
41, 2, 33imtr4g 298 . 2 (∀𝑥(𝜑𝜓) → (𝑡 ∈ {𝑥𝜑} → 𝑡 ∈ {𝑥𝜓}))
54ssrdv 3937 1 (∀𝑥(𝜑𝜓) → {𝑥𝜑} ⊆ {𝑥𝜓})
Colors of variables: wff setvar class
Syntax hints:  wi 4  wal 1552  [wsb 2084  wcel 2136  {cab 2734  wss 3899
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1809  ax-4 1823  ax-5 1924
This theorem depends on definitions:  df-bi 209  df-an 399  df-sb 2085  df-clab 2735  df-ss 3916
This theorem is referenced by:  ss2rabd  4020  moabex  5419
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