Theorem equsb1vOLD 2113

Description: Obsolete version of equsb1v 2112 as of 22-Jul-2023. Version of equsb1 2530 with a disjoint variable condition, which neither requires ax-12 2177 nor ax-13 2390. (Contributed by BJ, 11-Sep-2019.) Remove dependencies on axioms. (Revised by Wolf Lammen, 30-May-2023.) (Proof shortened by Steven Nguyen, 19-Jun-2023.) Revise df-sb 2070. (Revised by Steven Nguyen, 11-Jul-2023.) (Proof modification is discouraged.) (New usage is discouraged.)

Assertion

Ref	Expression
equsb1vOLD	⊢ [𝑦 / 𝑥]𝑥 = 𝑦

Distinct variable group:   𝑥,𝑦

Proof of Theorem equsb1vOLD

Step	Hyp	Ref	Expression
1		sb2vOLD 2097	. 2 ⊢ (∀𝑥(𝑥 = 𝑦 → 𝑥 = 𝑦) → [𝑦 / 𝑥]𝑥 = 𝑦)
2		id 22	. 2 ⊢ (𝑥 = 𝑦 → 𝑥 = 𝑦)
3	1, 2	mpg 1798	1 ⊢ [𝑦 / 𝑥]𝑥 = 𝑦

Syntax hints:   → wi 4  [wsb 2069

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1796  ax-4 1810  ax-5 1911  ax-6 1970  ax-7 2015

This theorem depends on definitions:  df-bi 209  df-an 399  df-ex 1781  df-sb 2070

This theorem is referenced by: (None)