Theorem bds 15497

Description: Boundedness of a formula resulting from implicit substitution in a bounded formula. Note that the proof does not use ax-bdsb 15468; therefore, using implicit instead of explicit substitution when boundedness is important, one might avoid using ax-bdsb 15468. (Contributed by BJ, 19-Nov-2019.)

Hypotheses

Ref	Expression
bds.bd	⊢ BOUNDED 𝜑
bds.1	⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓))

Assertion

Ref	Expression
bds	⊢ BOUNDED 𝜓

Distinct variable groups:   𝜓,𝑥   𝜑,𝑦

Allowed substitution hints:   𝜑(𝑥)   𝜓(𝑦)

Proof of Theorem bds

Step	Hyp	Ref	Expression
1		bds.bd	. . . 4 ⊢ BOUNDED 𝜑
2	1	bdcab 15495	. . 3 ⊢ BOUNDED {𝑥 ∣ 𝜑}
3		bds.1	. . . 4 ⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓))
4	3	cbvabv 2321	. . 3 ⊢ {𝑥 ∣ 𝜑} = {𝑦 ∣ 𝜓}
5	2, 4	bdceqi 15489	. 2 ⊢ BOUNDED {𝑦 ∣ 𝜓}
6	5	bdph 15496	1 ⊢ BOUNDED 𝜓

Syntax hints:   → wi 4   ↔ wb 105  {cab 2182  BOUNDED wbd 15458

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 710  ax-5 1461  ax-7 1462  ax-gen 1463  ax-ie1 1507  ax-ie2 1508  ax-8 1518  ax-10 1519  ax-11 1520  ax-i12 1521  ax-bndl 1523  ax-4 1524  ax-17 1540  ax-i9 1544  ax-ial 1548  ax-i5r 1549  ax-ext 2178  ax-bd0 15459  ax-bdsb 15468

This theorem depends on definitions:  df-bi 117  df-nf 1475  df-sb 1777  df-clab 2183  df-cleq 2189  df-clel 2192  df-bdc 15487

This theorem is referenced by: (None)