Theorem ssrabeq 3020

Description: If the restricting class of a restricted class abstraction is a subset of this restricted class abstraction, it is equal to this restricted class abstraction. (Contributed by Alexander van der Vekens, 31-Dec-2017.)

Assertion

Ref	Expression
ssrabeq	⊢ (𝑉 ⊆ {x ∈ 𝑉 ∣ φ} ↔ 𝑉 = {x ∈ 𝑉 ∣ φ})

Distinct variable group:   x,𝑉

Allowed substitution hint:   φ(x)

Proof of Theorem ssrabeq

Step	Hyp	Ref	Expression
1		ssrab2 3019	. . 3 ⊢ {x ∈ 𝑉 ∣ φ} ⊆ 𝑉
2	1	biantru 286	. 2 ⊢ (𝑉 ⊆ {x ∈ 𝑉 ∣ φ} ↔ (𝑉 ⊆ {x ∈ 𝑉 ∣ φ} ∧ {x ∈ 𝑉 ∣ φ} ⊆ 𝑉))
3		eqss 2954	. 2 ⊢ (𝑉 = {x ∈ 𝑉 ∣ φ} ↔ (𝑉 ⊆ {x ∈ 𝑉 ∣ φ} ∧ {x ∈ 𝑉 ∣ φ} ⊆ 𝑉))
4	2, 3	bitr4i 176	1 ⊢ (𝑉 ⊆ {x ∈ 𝑉 ∣ φ} ↔ 𝑉 = {x ∈ 𝑉 ∣ φ})

Syntax hints:   ∧ wa 97   ↔ wb 98   = wceq 1242  {crab 2304   ⊆ wss 2911

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-io 629  ax-5 1333  ax-7 1334  ax-gen 1335  ax-ie1 1379  ax-ie2 1380  ax-8 1392  ax-10 1393  ax-11 1394  ax-i12 1395  ax-bnd 1396  ax-4 1397  ax-17 1416  ax-i9 1420  ax-ial 1424  ax-i5r 1425  ax-ext 2019

This theorem depends on definitions:  df-bi 110  df-nf 1347  df-sb 1643  df-clab 2024  df-cleq 2030  df-clel 2033  df-nfc 2164  df-rab 2309  df-in 2918  df-ss 2925

This theorem is referenced by:  difrab0eqim  3282