Users' Mathboxes Mathbox for BJ < Previous   Next >
Nearby theorems
Mirrors  >  Home  >  MPE Home  >  Th. List  >   Mathboxes  >  df-bj-tag Structured version   Visualization version   GIF version

Definition df-bj-tag 35658
Description: Definition of the tagged copy of a class, that is, the adjunction to (an isomorph of) 𝐴 of a disjoint element (here, the empty set). Remark: this could be used for the one-point compactification of a topological space. (Contributed by BJ, 6-Oct-2018.)
Assertion
Ref Expression
df-bj-tag tag 𝐴 = (sngl 𝐴 ∪ {∅})

Detailed syntax breakdown of Definition df-bj-tag
StepHypRef Expression
1 cA . . 3 class 𝐴
21bj-ctag 35657 . 2 class tag 𝐴
31bj-csngl 35648 . . 3 class sngl 𝐴
4 c0 4318 . . . 4 class
54csn 4622 . . 3 class {∅}
63, 5cun 3942 . 2 class (sngl 𝐴 ∪ {∅})
72, 6wceq 1541 1 wff tag 𝐴 = (sngl 𝐴 ∪ {∅})
Colors of variables: wff setvar class
This definition is referenced by:  bj-tageq  35659  bj-eltag  35660  bj-0eltag  35661  bj-tagss  35663  bj-snglsstag  35664  bj-sngltag  35666  bj-tagex  35670
  Copyright terms: Public domain W3C validator