Definition df-bj-rrhat 36111

Description: Define the real projective line. (Contributed by BJ, 27-Jun-2019.)

Assertion

Ref	Expression
df-bj-rrhat	⊢ ℝ̂ = (ℝ ∪ {∞})

Detailed syntax breakdown of Definition df-bj-rrhat

Step	Hyp	Ref	Expression
1		crrhat 36110	. 2 class ℝ̂
2		cr 11108	. . 3 class ℝ
3		cinfty 36106	. . . 4 class ∞
4	3	csn 4628	. . 3 class {∞}
5	2, 4	cun 3946	. 2 class (ℝ ∪ {∞})
6	1, 5	wceq 1541	1 wff ℝ̂ = (ℝ ∪ {∞})

This definition is referenced by:  bj-rrhatsscchat  36112