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Description: The center of a group is an abelian group. (Contributed by Thierry Arnoux, 21-Aug-2023)
| Ref | Expression | ||
|---|---|---|---|
| Hypothesis | cntrcmnd.z | ⊢ 𝑍 = ( 𝑀 ↾s ( Cntr ‘ 𝑀 ) ) | |
| Assertion | cntrabl | ⊢ ( 𝑀 ∈ Grp → 𝑍 ∈ Abel ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | cntrcmnd.z | ⊢ 𝑍 = ( 𝑀 ↾s ( Cntr ‘ 𝑀 ) ) | |
| 2 | eqid | ⊢ ( Base ‘ 𝑀 ) = ( Base ‘ 𝑀 ) | |
| 3 | eqid | ⊢ ( Cntz ‘ 𝑀 ) = ( Cntz ‘ 𝑀 ) | |
| 4 | 2 3 | cntrval | ⊢ ( ( Cntz ‘ 𝑀 ) ‘ ( Base ‘ 𝑀 ) ) = ( Cntr ‘ 𝑀 ) |
| 5 | ssid | ⊢ ( Base ‘ 𝑀 ) ⊆ ( Base ‘ 𝑀 ) | |
| 6 | 2 3 | cntzsubg | ⊢ ( ( 𝑀 ∈ Grp ∧ ( Base ‘ 𝑀 ) ⊆ ( Base ‘ 𝑀 ) ) → ( ( Cntz ‘ 𝑀 ) ‘ ( Base ‘ 𝑀 ) ) ∈ ( SubGrp ‘ 𝑀 ) ) |
| 7 | 5 6 | mpan2 | ⊢ ( 𝑀 ∈ Grp → ( ( Cntz ‘ 𝑀 ) ‘ ( Base ‘ 𝑀 ) ) ∈ ( SubGrp ‘ 𝑀 ) ) |
| 8 | 4 7 | eqeltrrid | ⊢ ( 𝑀 ∈ Grp → ( Cntr ‘ 𝑀 ) ∈ ( SubGrp ‘ 𝑀 ) ) |
| 9 | 1 | subggrp | ⊢ ( ( Cntr ‘ 𝑀 ) ∈ ( SubGrp ‘ 𝑀 ) → 𝑍 ∈ Grp ) |
| 10 | 8 9 | syl | ⊢ ( 𝑀 ∈ Grp → 𝑍 ∈ Grp ) |
| 11 | grpmnd | ⊢ ( 𝑀 ∈ Grp → 𝑀 ∈ Mnd ) | |
| 12 | 1 | cntrcmnd | ⊢ ( 𝑀 ∈ Mnd → 𝑍 ∈ CMnd ) |
| 13 | 11 12 | syl | ⊢ ( 𝑀 ∈ Grp → 𝑍 ∈ CMnd ) |
| 14 | isabl | ⊢ ( 𝑍 ∈ Abel ↔ ( 𝑍 ∈ Grp ∧ 𝑍 ∈ CMnd ) ) | |
| 15 | 10 13 14 | sylanbrc | ⊢ ( 𝑀 ∈ Grp → 𝑍 ∈ Abel ) |