Theorem equsexvw 2015

Description: Version of equsexv 2293 with a disjoint variable condition, and of equsex 2439 with two disjoint variable conditions, which requires fewer axioms. See also the dual form equsalvw 2014. (Contributed by BJ, 31-May-2019.) (Proof shortened by Wolf Lammen, 23-Oct-2023.)

Hypothesis

Ref	Expression
equsalvw.1	⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓))

Assertion

Ref	Expression
equsexvw	⊢ (∃𝑥(𝑥 = 𝑦 ∧ 𝜑) ↔ 𝜓)

Distinct variable groups:   𝑥,𝑦   𝜓,𝑥

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

Proof of Theorem equsexvw

Step	Hyp	Ref	Expression
1		alinexa 1853	. . 3 ⊢ (∀𝑥(𝑥 = 𝑦 → ¬ 𝜑) ↔ ¬ ∃𝑥(𝑥 = 𝑦 ∧ 𝜑))
2		equsalvw.1	. . . . 5 ⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓))
3	2	notbid 320	. . . 4 ⊢ (𝑥 = 𝑦 → (¬ 𝜑 ↔ ¬ 𝜓))
4	3	equsalvw 2014	. . 3 ⊢ (∀𝑥(𝑥 = 𝑦 → ¬ 𝜑) ↔ ¬ 𝜓)
5	1, 4	bitr3i 279	. 2 ⊢ (¬ ∃𝑥(𝑥 = 𝑦 ∧ 𝜑) ↔ ¬ 𝜓)
6	5	con4bii 323	1 ⊢ (∃𝑥(𝑥 = 𝑦 ∧ 𝜑) ↔ 𝜓)

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 208   ∧ wa 398  ∀wal 1548  ∃wex 1789

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1805  ax-4 1819  ax-5 1920  ax-6 1977

This theorem depends on definitions:  df-bi 209  df-an 399  df-ex 1790

This theorem is referenced by:  equvinv  2039  cleljust  2141  sbelx  2278  cleljustab  2733  axsepgfromrep  5234  dfid3  5534  opeliunxp  5703  opeliun2xp  5704  imai  6049  coi1  6235  opabex3d  7931  opabex3rd  7932  opabex3  7933  fsplit  8080  mapsnend  9002  elirrv  9531  elirrvOLD  9532  dfac5lem1  10065  dfac5lem3  10067  dffix2  36191  sscoid  36199  elfuns  36201  pmapglb  40332  polval2N  40468  tfsconcat0i  43860