Metamath Proof Explorer


Definition df-nelbr

Description: Define negated membership as binary relation. Analogous to df-eprel (the membership relation). (Contributed by AV, 26-Dec-2021)

Ref Expression
Assertion df-nelbr ⊢ ∉ = x y | ¬ x ∈ y

Detailed syntax breakdown

Step Hyp Ref Expression
0 cnelbr class ∉
1 vx setvar x
2 vy setvar y
3 1 cv setvar x
4 2 cv setvar y
5 3 4 wcel wff x ∈ y
6 5 wn wff ¬ x ∈ y
7 6 1 2 copab class x y | ¬ x ∈ y
8 0 7 wceq wff ∉ = x y | ¬ x ∈ y