Definition df-iress 13035

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 13028	. 2 class ↾s
2		vw	. . 3 setvar w
3		vx	. . 3 setvar x
4		cvv 2799	. . 3 class _V
5	2	cv 1394	. . . 4 class w
6		cnx 13024	. . . . . 6 class ndx
7		cbs 13027	. . . . . 6 class Base
8	6, 7	cfv 5317	. . . . 5 class ( Base ` ndx )
9	3	cv 1394	. . . . . 6 class x
10	5, 7	cfv 5317	. . . . . 6 class ( Base ` w )
11	9, 10	cin 3196	. . . . 5 class ( x i^i ( Base ` w ) )
12	8, 11	cop 3669	. . . 4 class <. ( Base ` ndx ) , ( x i^i ( Base ` w ) ) >.
13		csts 13025	. . . 4 class sSet
14	5, 12, 13	co 6000	. . 3 class ( w sSet <. ( Base ` ndx ) , ( x i^i ( Base ` w ) ) >. )
15	2, 3, 4, 4, 14	cmpo 6002	. 2 class ( w e. _V , x e. _V |-> ( w sSet <. ( Base ` ndx ) , ( x i^i ( Base ` w ) ) >. ) )
16	1, 15	wceq 1395	1 wff ↾s = ( w e. _V , x e. _V |-> ( w sSet <. ( Base ` ndx ) , ( x i^i ( Base ` w ) ) >. ) )

This definition is referenced by:  reldmress  13091  ressvalsets  13092