Definition df-iress 13360

Description: Define a multifunction restriction operator for extensible structures, which can be used to turn statements about rings into statements about subrings, modules into submodules, etc. This definition knows nothing about individual structures and merely truncates the Base set while leaving operators alone; individual kinds of structures will need to handle this behavior, by ignoring operators' values outside the range, defining a function using the base set and applying that, or explicitly truncating the slot before use.

(Credit for this operator, as well as the 2023 modification for iset.mm, goes to Mario Carneiro.)

(Contributed by Stefan O'Rear, 29-Nov-2014.) (Revised by Jim Kingdon, 7-Oct-2023.)

Assertion

Ref	Expression
df-iress	|- ↾s = ( w e. _V , x e. _V |-> ( w sSet <. ( Base ` ndx ) , ( x i^i ( Base ` w ) ) >. ) )

Distinct variable group:   x, w

Detailed syntax breakdown of Definition df-iress

Step	Hyp	Ref	Expression
1		cress 13353	. 2 class ↾s
2		vw	. . 3 setvar w
3		vx	. . 3 setvar x
4		cvv 2821	. . 3 class _V
5	2	cv 1401	. . . 4 class w
6		cnx 13349	. . . . . 6 class ndx
7		cbs 13352	. . . . . 6 class Base
8	6, 7	cfv 5377	. . . . 5 class ( Base ` ndx )
9	3	cv 1401	. . . . . 6 class x
10	5, 7	cfv 5377	. . . . . 6 class ( Base ` w )
11	9, 10	cin 3219	. . . . 5 class ( x i^i ( Base ` w ) )
12	8, 11	cop 3712	. . . 4 class <. ( Base ` ndx ) , ( x i^i ( Base ` w ) ) >.
13		csts 13350	. . . 4 class sSet
14	5, 12, 13	co 6085	. . 3 class ( w sSet <. ( Base ` ndx ) , ( x i^i ( Base ` w ) ) >. )
15	2, 3, 4, 4, 14	cmpo 6087	. 2 class ( w e. _V , x e. _V |-> ( w sSet <. ( Base ` ndx ) , ( x i^i ( Base ` w ) ) >. ) )
16	1, 15	wceq 1402	1 wff ↾s = ( w e. _V , x e. _V |-> ( w sSet <. ( Base ` ndx ) , ( x i^i ( Base ` w ) ) >. ) )

This definition is used by:  reldmress  13417  ressvalsets  13418