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Description: Define the image of a class (as restricted by another class). Definition 6.6(2) of TakeutiZaring p. 24. For example, ( F = { <. 2 , 6 >. , <. 3 , 9 >. } /\ B = { 1 , 2 } ) -> ( F " B ) = { 6 } ( ex-ima ). Contrast with restriction ( df-res ) and range ( df-rn ). For an alternate definition, see dfima2 . (Contributed by NM, 2-Aug-1994)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | df-ima | ⊢ ( 𝐴 “ 𝐵 ) = ran ( 𝐴 ↾ 𝐵 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 0 | cA | ⊢ 𝐴 | |
| 1 | cB | ⊢ 𝐵 | |
| 2 | 0 1 | cima | ⊢ ( 𝐴 “ 𝐵 ) |
| 3 | 0 1 | cres | ⊢ ( 𝐴 ↾ 𝐵 ) |
| 4 | 3 | crn | ⊢ ran ( 𝐴 ↾ 𝐵 ) |
| 5 | 2 4 | wceq | ⊢ ( 𝐴 “ 𝐵 ) = ran ( 𝐴 ↾ 𝐵 ) |