Detailed syntax breakdown of Definition df-topsp
| Step | Hyp | Ref
 | Expression | 
| 1 |   | ctps 14266 | 
. 2
class
TopSp | 
| 2 |   | vf | 
. . . . . 6
setvar 𝑓 | 
| 3 | 2 | cv 1363 | 
. . . . 5
class 𝑓 | 
| 4 |   | ctopn 12911 | 
. . . . 5
class
TopOpen | 
| 5 | 3, 4 | cfv 5258 | 
. . . 4
class
(TopOpen‘𝑓) | 
| 6 |   | cbs 12678 | 
. . . . . 6
class
Base | 
| 7 | 3, 6 | cfv 5258 | 
. . . . 5
class
(Base‘𝑓) | 
| 8 |   | ctopon 14246 | 
. . . . 5
class
TopOn | 
| 9 | 7, 8 | cfv 5258 | 
. . . 4
class
(TopOn‘(Base‘𝑓)) | 
| 10 | 5, 9 | wcel 2167 | 
. . 3
wff
(TopOpen‘𝑓)
∈ (TopOn‘(Base‘𝑓)) | 
| 11 | 10, 2 | cab 2182 | 
. 2
class {𝑓 ∣ (TopOpen‘𝑓) ∈
(TopOn‘(Base‘𝑓))} | 
| 12 | 1, 11 | wceq 1364 | 
1
wff TopSp =
{𝑓 ∣
(TopOpen‘𝑓) ∈
(TopOn‘(Base‘𝑓))} |