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Theorem ss2abim 4011
Description: Class abstractions in a subclass relationship. Reverse direction of ss2ab 4012 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 2109 . . 3 (∀𝑥(𝜑𝜓) → ([𝑡 / 𝑥]𝜑 → [𝑡 / 𝑥]𝜓))
2 df-clab 2741 . . 3 (𝑡 ∈ {𝑥𝜑} ↔ [𝑡 / 𝑥]𝜑)
3 df-clab 2741 . . 3 (𝑡 ∈ {𝑥𝜓} ↔ [𝑡 / 𝑥]𝜓)
41, 2, 33imtr4g 299 . 2 (∀𝑥(𝜑𝜓) → (𝑡 ∈ {𝑥𝜑} → 𝑡 ∈ {𝑥𝜓}))
54ssrdv 3940 1 (∀𝑥(𝜑𝜓) → {𝑥𝜑} ⊆ {𝑥𝜓})
Colors of variables:    wff setvar class
This proof depends on syntax axioms:  wi 4  wal 1568  [wsb 2099  wcel 2145  {cab 2740  wss 3902
This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1828  ax-4 1842  ax-5 1943  ax-6 2000  ax-7 2041
This proof depends on definitions:  df-bi 210  df-an 402  df-ex 1813  df-sb 2100  df-clab 2741  df-ss 3919
This theorem is used by:  ss2rabd  4023  moabex  5437
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