Definition df-bj-1upl

Description: Definition of the Morse monuple (1-tuple). This is not useful per se, but is used as a step towards the definition of couples (2-tuples, or ordered pairs). The reason for "tagging" the set is so that an m-tuple and an n-tuple be equal only when m = n. Note that with this definition, the 0-tuple is the empty set. New usage is discouraged because the precise definition is generally unimportant compared to the characteristic properties bj-2upleq , bj-2uplth , bj-2uplex , and the properties of the projections (see df-bj-pr1 and df-bj-pr2 ). (Contributed by BJ, 6-Apr-2019) (New usage is discouraged.)

	Ref	Expression
Assertion	df-bj-1upl	|- (| A |) = ( { (/) } X. tag A )

Detailed syntax breakdown

Step	Hyp	Ref	Expression
0		cA	|- A
1	0	bj-c1upl	|- (| A |)
2		c0	|- (/)
3	2	csn	|- { (/) }
4	0	bj-ctag	|- tag A
5	3 4	cxp	|- ( { (/) } X. tag A )
6	1 5	wceq	|- (| A |) = ( { (/) } X. tag A )