Definition df-lsw 11014

Description: Extract the last symbol of a word. May be not meaningful for other sets which are not words. The name lastS (as abbreviation of "lastSymbol") is a compromise between usually used names for corresponding functions in computer programs (as last() or lastChar()), the terminology used for words in set.mm ("symbol" instead of "character") and brevity ("lastS" is shorter than "lastChar" and "lastSymbol"). Labels of theorems about last symbols of a word will contain the abbreviation "lsw" (Last Symbol of a Word). (Contributed by Alexander van der Vekens, 18-Mar-2018.)

Assertion

Ref	Expression
df-lsw	|- lastS = ( w e. _V |-> ( w ` ( (♯ ` w ) - 1 ) ) )

Detailed syntax breakdown of Definition df-lsw

Step	Hyp	Ref	Expression
1		clsw 11013	. 2 class lastS
2		vw	. . 3 setvar w
3		cvv 2771	. . 3 class _V
4	2	cv 1371	. . . . . 6 class w
5		chash 10901	. . . . . 6 class ♯
6	4, 5	cfv 5268	. . . . 5 class (♯ ` w )
7		c1 7908	. . . . 5 class 1
8		cmin 8225	. . . . 5 class -
9	6, 7, 8	co 5934	. . . 4 class ( (♯ ` w ) - 1 )
10	9, 4	cfv 5268	. . 3 class ( w ` ( (♯ ` w ) - 1 ) )
11	2, 3, 10	cmpt 4104	. 2 class ( w e. _V |-> ( w ` ( (♯ ` w ) - 1 ) ) )
12	1, 11	wceq 1372	1 wff lastS = ( w e. _V |-> ( w ` ( (♯ ` w ) - 1 ) ) )

This definition is referenced by:  lswwrd  11015