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Description: Closure of the operation of a group. (Contributed by SN, 29-Jul-2024)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | grpcld.b | ⊢ 𝐵 = ( Base ‘ 𝐺 ) | |
| grpcld.p | ⊢ + = ( +g ‘ 𝐺 ) | ||
| grpcld.r | ⊢ ( 𝜑 → 𝐺 ∈ Grp ) | ||
| grpcld.x | ⊢ ( 𝜑 → 𝑋 ∈ 𝐵 ) | ||
| grpcld.y | ⊢ ( 𝜑 → 𝑌 ∈ 𝐵 ) | ||
| Assertion | grpcld | ⊢ ( 𝜑 → ( 𝑋 + 𝑌 ) ∈ 𝐵 ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | grpcld.b | ⊢ 𝐵 = ( Base ‘ 𝐺 ) | |
| 2 | grpcld.p | ⊢ + = ( +g ‘ 𝐺 ) | |
| 3 | grpcld.r | ⊢ ( 𝜑 → 𝐺 ∈ Grp ) | |
| 4 | grpcld.x | ⊢ ( 𝜑 → 𝑋 ∈ 𝐵 ) | |
| 5 | grpcld.y | ⊢ ( 𝜑 → 𝑌 ∈ 𝐵 ) | |
| 6 | 1 2 | grpcl | ⊢ ( ( 𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( 𝑋 + 𝑌 ) ∈ 𝐵 ) |
| 7 | 3 4 5 6 | syl3anc | ⊢ ( 𝜑 → ( 𝑋 + 𝑌 ) ∈ 𝐵 ) |