Definition df-lng

Description: Define the line index extractor for geometries. (Contributed by Thierry Arnoux, 27-Mar-2019) Use its index-independent form lngid instead. (New usage is discouraged.)

	Ref	Expression
Assertion	df-lng	$$⊢{Line}_{𝒢}=\mathrm{Slot}17$$

Detailed syntax breakdown

Step	Hyp	Ref	Expression
0		clng	$$class{Line}_{𝒢}$$
1		c1	$$class1$$
2		c7	$$class7$$
3	1 2	cdc	$$class17$$
4	3	cslot	$$class\mathrm{Slot}17$$
5	0 4	wceq	$$wff{Line}_{𝒢}=\mathrm{Slot}17$$