Definition df-bj-rrhat 33122

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

Assertion

Ref	Expression
df-bj-rrhat	|- RRhat = ( RR u. {infty } )

Detailed syntax breakdown of Definition df-bj-rrhat

Step	Hyp	Ref	Expression
1		crrhat 33121	. 2 class RRhat
2		cr 9935	. . 3 class RR
3		cinfty 33117	. . . 4 class infty
4	3	csn 4177	. . 3 class {infty }
5	2, 4	cun 3572	. 2 class ( RR u. {infty } )
6	1, 5	wceq 1483	1 wff RRhat = ( RR u. {infty } )

This definition is referenced by:  bj-rrhatsscchat  33123