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Description: The involution function in a star ring is closed in the ring. (Contributed by Mario Carneiro, 6-Oct-2015)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | srngcl.i | ⊢ ∗ = ( *𝑟 ‘ 𝑅 ) | |
| srngcl.b | ⊢ 𝐵 = ( Base ‘ 𝑅 ) | ||
| Assertion | srngcl | ⊢ ( ( 𝑅 ∈ *-Ring ∧ 𝑋 ∈ 𝐵 ) → ( ∗ ‘ 𝑋 ) ∈ 𝐵 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | srngcl.i | ⊢ ∗ = ( *𝑟 ‘ 𝑅 ) | |
| 2 | srngcl.b | ⊢ 𝐵 = ( Base ‘ 𝑅 ) | |
| 3 | eqid | ⊢ ( *rf ‘ 𝑅 ) = ( *rf ‘ 𝑅 ) | |
| 4 | 2 1 3 | stafval | ⊢ ( 𝑋 ∈ 𝐵 → ( ( *rf ‘ 𝑅 ) ‘ 𝑋 ) = ( ∗ ‘ 𝑋 ) ) |
| 5 | 4 | adantl | ⊢ ( ( 𝑅 ∈ *-Ring ∧ 𝑋 ∈ 𝐵 ) → ( ( *rf ‘ 𝑅 ) ‘ 𝑋 ) = ( ∗ ‘ 𝑋 ) ) |
| 6 | 3 2 | srngf1o | ⊢ ( 𝑅 ∈ *-Ring → ( *rf ‘ 𝑅 ) : 𝐵 –1-1-onto→ 𝐵 ) |
| 7 | f1of | ⊢ ( ( *rf ‘ 𝑅 ) : 𝐵 –1-1-onto→ 𝐵 → ( *rf ‘ 𝑅 ) : 𝐵 ⟶ 𝐵 ) | |
| 8 | 6 7 | syl | ⊢ ( 𝑅 ∈ *-Ring → ( *rf ‘ 𝑅 ) : 𝐵 ⟶ 𝐵 ) |
| 9 | 8 | ffvelcdmda | ⊢ ( ( 𝑅 ∈ *-Ring ∧ 𝑋 ∈ 𝐵 ) → ( ( *rf ‘ 𝑅 ) ‘ 𝑋 ) ∈ 𝐵 ) |
| 10 | 5 9 | eqeltrrd | ⊢ ( ( 𝑅 ∈ *-Ring ∧ 𝑋 ∈ 𝐵 ) → ( ∗ ‘ 𝑋 ) ∈ 𝐵 ) |