Definition df-iress 12811

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 12804	. 2 class ↾s
2		vw	. . 3 setvar w
3		vx	. . 3 setvar x
4		cvv 2771	. . 3 class _V
5	2	cv 1371	. . . 4 class w
6		cnx 12800	. . . . . 6 class ndx
7		cbs 12803	. . . . . 6 class Base
8	6, 7	cfv 5270	. . . . 5 class ( Base ` ndx )
9	3	cv 1371	. . . . . 6 class x
10	5, 7	cfv 5270	. . . . . 6 class ( Base ` w )
11	9, 10	cin 3164	. . . . 5 class ( x i^i ( Base ` w ) )
12	8, 11	cop 3635	. . . 4 class <. ( Base ` ndx ) , ( x i^i ( Base ` w ) ) >.
13		csts 12801	. . . 4 class sSet
14	5, 12, 13	co 5943	. . 3 class ( w sSet <. ( Base ` ndx ) , ( x i^i ( Base ` w ) ) >. )
15	2, 3, 4, 4, 14	cmpo 5945	. 2 class ( w e. _V , x e. _V |-> ( w sSet <. ( Base ` ndx ) , ( x i^i ( Base ` w ) ) >. ) )
16	1, 15	wceq 1372	1 wff ↾s = ( w e. _V , x e. _V |-> ( w sSet <. ( Base ` ndx ) , ( x i^i ( Base ` w ) ) >. ) )

This definition is referenced by:  reldmress  12866  ressvalsets  12867