| Step | Hyp | Ref | Expression | 
						
							| 1 |  | 2zrng.e | ⊢ 𝐸  =  { 𝑧  ∈  ℤ  ∣  ∃ 𝑥  ∈  ℤ 𝑧  =  ( 2  ·  𝑥 ) } | 
						
							| 2 |  | 2zrngbas.r | ⊢ 𝑅  =  ( ℂfld  ↾s  𝐸 ) | 
						
							| 3 |  | eqeq1 | ⊢ ( 𝑧  =  𝑎  →  ( 𝑧  =  ( 2  ·  𝑥 )  ↔  𝑎  =  ( 2  ·  𝑥 ) ) ) | 
						
							| 4 | 3 | rexbidv | ⊢ ( 𝑧  =  𝑎  →  ( ∃ 𝑥  ∈  ℤ 𝑧  =  ( 2  ·  𝑥 )  ↔  ∃ 𝑥  ∈  ℤ 𝑎  =  ( 2  ·  𝑥 ) ) ) | 
						
							| 5 | 4 1 | elrab2 | ⊢ ( 𝑎  ∈  𝐸  ↔  ( 𝑎  ∈  ℤ  ∧  ∃ 𝑥  ∈  ℤ 𝑎  =  ( 2  ·  𝑥 ) ) ) | 
						
							| 6 |  | eqeq1 | ⊢ ( 𝑧  =  𝑏  →  ( 𝑧  =  ( 2  ·  𝑥 )  ↔  𝑏  =  ( 2  ·  𝑥 ) ) ) | 
						
							| 7 | 6 | rexbidv | ⊢ ( 𝑧  =  𝑏  →  ( ∃ 𝑥  ∈  ℤ 𝑧  =  ( 2  ·  𝑥 )  ↔  ∃ 𝑥  ∈  ℤ 𝑏  =  ( 2  ·  𝑥 ) ) ) | 
						
							| 8 | 7 1 | elrab2 | ⊢ ( 𝑏  ∈  𝐸  ↔  ( 𝑏  ∈  ℤ  ∧  ∃ 𝑥  ∈  ℤ 𝑏  =  ( 2  ·  𝑥 ) ) ) | 
						
							| 9 |  | oveq2 | ⊢ ( 𝑥  =  𝑦  →  ( 2  ·  𝑥 )  =  ( 2  ·  𝑦 ) ) | 
						
							| 10 | 9 | eqeq2d | ⊢ ( 𝑥  =  𝑦  →  ( 𝑎  =  ( 2  ·  𝑥 )  ↔  𝑎  =  ( 2  ·  𝑦 ) ) ) | 
						
							| 11 | 10 | cbvrexvw | ⊢ ( ∃ 𝑥  ∈  ℤ 𝑎  =  ( 2  ·  𝑥 )  ↔  ∃ 𝑦  ∈  ℤ 𝑎  =  ( 2  ·  𝑦 ) ) | 
						
							| 12 |  | zaddcl | ⊢ ( ( 𝑎  ∈  ℤ  ∧  𝑏  ∈  ℤ )  →  ( 𝑎  +  𝑏 )  ∈  ℤ ) | 
						
							| 13 | 12 | ancoms | ⊢ ( ( 𝑏  ∈  ℤ  ∧  𝑎  ∈  ℤ )  →  ( 𝑎  +  𝑏 )  ∈  ℤ ) | 
						
							| 14 | 13 | adantr | ⊢ ( ( ( 𝑏  ∈  ℤ  ∧  𝑎  ∈  ℤ )  ∧  ( ∃ 𝑥  ∈  ℤ 𝑏  =  ( 2  ·  𝑥 )  ∧  ∃ 𝑦  ∈  ℤ 𝑎  =  ( 2  ·  𝑦 ) ) )  →  ( 𝑎  +  𝑏 )  ∈  ℤ ) | 
						
							| 15 |  | simpl | ⊢ ( ( 𝑦  ∈  ℤ  ∧  𝑎  =  ( 2  ·  𝑦 ) )  →  𝑦  ∈  ℤ ) | 
						
							| 16 |  | simpl | ⊢ ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  →  𝑥  ∈  ℤ ) | 
						
							| 17 |  | zaddcl | ⊢ ( ( 𝑦  ∈  ℤ  ∧  𝑥  ∈  ℤ )  →  ( 𝑦  +  𝑥 )  ∈  ℤ ) | 
						
							| 18 | 15 16 17 | syl2anr | ⊢ ( ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  ∧  ( 𝑦  ∈  ℤ  ∧  𝑎  =  ( 2  ·  𝑦 ) ) )  →  ( 𝑦  +  𝑥 )  ∈  ℤ ) | 
						
							| 19 | 18 | adantr | ⊢ ( ( ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  ∧  ( 𝑦  ∈  ℤ  ∧  𝑎  =  ( 2  ·  𝑦 ) ) )  ∧  ( 𝑏  ∈  ℤ  ∧  𝑎  ∈  ℤ ) )  →  ( 𝑦  +  𝑥 )  ∈  ℤ ) | 
						
							| 20 |  | oveq2 | ⊢ ( 𝑧  =  ( 𝑦  +  𝑥 )  →  ( 2  ·  𝑧 )  =  ( 2  ·  ( 𝑦  +  𝑥 ) ) ) | 
						
							| 21 | 20 | eqeq2d | ⊢ ( 𝑧  =  ( 𝑦  +  𝑥 )  →  ( ( 2  ·  ( 𝑦  +  𝑥 ) )  =  ( 2  ·  𝑧 )  ↔  ( 2  ·  ( 𝑦  +  𝑥 ) )  =  ( 2  ·  ( 𝑦  +  𝑥 ) ) ) ) | 
						
							| 22 | 21 | adantl | ⊢ ( ( ( ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  ∧  ( 𝑦  ∈  ℤ  ∧  𝑎  =  ( 2  ·  𝑦 ) ) )  ∧  ( 𝑏  ∈  ℤ  ∧  𝑎  ∈  ℤ ) )  ∧  𝑧  =  ( 𝑦  +  𝑥 ) )  →  ( ( 2  ·  ( 𝑦  +  𝑥 ) )  =  ( 2  ·  𝑧 )  ↔  ( 2  ·  ( 𝑦  +  𝑥 ) )  =  ( 2  ·  ( 𝑦  +  𝑥 ) ) ) ) | 
						
							| 23 |  | eqidd | ⊢ ( ( ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  ∧  ( 𝑦  ∈  ℤ  ∧  𝑎  =  ( 2  ·  𝑦 ) ) )  ∧  ( 𝑏  ∈  ℤ  ∧  𝑎  ∈  ℤ ) )  →  ( 2  ·  ( 𝑦  +  𝑥 ) )  =  ( 2  ·  ( 𝑦  +  𝑥 ) ) ) | 
						
							| 24 | 19 22 23 | rspcedvd | ⊢ ( ( ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  ∧  ( 𝑦  ∈  ℤ  ∧  𝑎  =  ( 2  ·  𝑦 ) ) )  ∧  ( 𝑏  ∈  ℤ  ∧  𝑎  ∈  ℤ ) )  →  ∃ 𝑧  ∈  ℤ ( 2  ·  ( 𝑦  +  𝑥 ) )  =  ( 2  ·  𝑧 ) ) | 
						
							| 25 |  | simpr | ⊢ ( ( 𝑦  ∈  ℤ  ∧  𝑎  =  ( 2  ·  𝑦 ) )  →  𝑎  =  ( 2  ·  𝑦 ) ) | 
						
							| 26 |  | simpr | ⊢ ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  →  𝑏  =  ( 2  ·  𝑥 ) ) | 
						
							| 27 | 25 26 | oveqan12rd | ⊢ ( ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  ∧  ( 𝑦  ∈  ℤ  ∧  𝑎  =  ( 2  ·  𝑦 ) ) )  →  ( 𝑎  +  𝑏 )  =  ( ( 2  ·  𝑦 )  +  ( 2  ·  𝑥 ) ) ) | 
						
							| 28 | 27 | adantr | ⊢ ( ( ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  ∧  ( 𝑦  ∈  ℤ  ∧  𝑎  =  ( 2  ·  𝑦 ) ) )  ∧  ( 𝑏  ∈  ℤ  ∧  𝑎  ∈  ℤ ) )  →  ( 𝑎  +  𝑏 )  =  ( ( 2  ·  𝑦 )  +  ( 2  ·  𝑥 ) ) ) | 
						
							| 29 |  | 2cnd | ⊢ ( ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  ∧  ( 𝑦  ∈  ℤ  ∧  𝑎  =  ( 2  ·  𝑦 ) ) )  →  2  ∈  ℂ ) | 
						
							| 30 |  | zcn | ⊢ ( 𝑦  ∈  ℤ  →  𝑦  ∈  ℂ ) | 
						
							| 31 | 30 | adantr | ⊢ ( ( 𝑦  ∈  ℤ  ∧  𝑎  =  ( 2  ·  𝑦 ) )  →  𝑦  ∈  ℂ ) | 
						
							| 32 | 31 | adantl | ⊢ ( ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  ∧  ( 𝑦  ∈  ℤ  ∧  𝑎  =  ( 2  ·  𝑦 ) ) )  →  𝑦  ∈  ℂ ) | 
						
							| 33 |  | zcn | ⊢ ( 𝑥  ∈  ℤ  →  𝑥  ∈  ℂ ) | 
						
							| 34 | 33 | adantr | ⊢ ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  →  𝑥  ∈  ℂ ) | 
						
							| 35 | 34 | adantr | ⊢ ( ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  ∧  ( 𝑦  ∈  ℤ  ∧  𝑎  =  ( 2  ·  𝑦 ) ) )  →  𝑥  ∈  ℂ ) | 
						
							| 36 | 29 32 35 | adddid | ⊢ ( ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  ∧  ( 𝑦  ∈  ℤ  ∧  𝑎  =  ( 2  ·  𝑦 ) ) )  →  ( 2  ·  ( 𝑦  +  𝑥 ) )  =  ( ( 2  ·  𝑦 )  +  ( 2  ·  𝑥 ) ) ) | 
						
							| 37 | 36 | adantr | ⊢ ( ( ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  ∧  ( 𝑦  ∈  ℤ  ∧  𝑎  =  ( 2  ·  𝑦 ) ) )  ∧  ( 𝑏  ∈  ℤ  ∧  𝑎  ∈  ℤ ) )  →  ( 2  ·  ( 𝑦  +  𝑥 ) )  =  ( ( 2  ·  𝑦 )  +  ( 2  ·  𝑥 ) ) ) | 
						
							| 38 | 28 37 | eqtr4d | ⊢ ( ( ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  ∧  ( 𝑦  ∈  ℤ  ∧  𝑎  =  ( 2  ·  𝑦 ) ) )  ∧  ( 𝑏  ∈  ℤ  ∧  𝑎  ∈  ℤ ) )  →  ( 𝑎  +  𝑏 )  =  ( 2  ·  ( 𝑦  +  𝑥 ) ) ) | 
						
							| 39 | 38 | eqeq1d | ⊢ ( ( ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  ∧  ( 𝑦  ∈  ℤ  ∧  𝑎  =  ( 2  ·  𝑦 ) ) )  ∧  ( 𝑏  ∈  ℤ  ∧  𝑎  ∈  ℤ ) )  →  ( ( 𝑎  +  𝑏 )  =  ( 2  ·  𝑧 )  ↔  ( 2  ·  ( 𝑦  +  𝑥 ) )  =  ( 2  ·  𝑧 ) ) ) | 
						
							| 40 | 39 | rexbidv | ⊢ ( ( ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  ∧  ( 𝑦  ∈  ℤ  ∧  𝑎  =  ( 2  ·  𝑦 ) ) )  ∧  ( 𝑏  ∈  ℤ  ∧  𝑎  ∈  ℤ ) )  →  ( ∃ 𝑧  ∈  ℤ ( 𝑎  +  𝑏 )  =  ( 2  ·  𝑧 )  ↔  ∃ 𝑧  ∈  ℤ ( 2  ·  ( 𝑦  +  𝑥 ) )  =  ( 2  ·  𝑧 ) ) ) | 
						
							| 41 | 24 40 | mpbird | ⊢ ( ( ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  ∧  ( 𝑦  ∈  ℤ  ∧  𝑎  =  ( 2  ·  𝑦 ) ) )  ∧  ( 𝑏  ∈  ℤ  ∧  𝑎  ∈  ℤ ) )  →  ∃ 𝑧  ∈  ℤ ( 𝑎  +  𝑏 )  =  ( 2  ·  𝑧 ) ) | 
						
							| 42 | 41 | ex | ⊢ ( ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  ∧  ( 𝑦  ∈  ℤ  ∧  𝑎  =  ( 2  ·  𝑦 ) ) )  →  ( ( 𝑏  ∈  ℤ  ∧  𝑎  ∈  ℤ )  →  ∃ 𝑧  ∈  ℤ ( 𝑎  +  𝑏 )  =  ( 2  ·  𝑧 ) ) ) | 
						
							| 43 | 42 | rexlimdvaa | ⊢ ( ( 𝑥  ∈  ℤ  ∧  𝑏  =  ( 2  ·  𝑥 ) )  →  ( ∃ 𝑦  ∈  ℤ 𝑎  =  ( 2  ·  𝑦 )  →  ( ( 𝑏  ∈  ℤ  ∧  𝑎  ∈  ℤ )  →  ∃ 𝑧  ∈  ℤ ( 𝑎  +  𝑏 )  =  ( 2  ·  𝑧 ) ) ) ) | 
						
							| 44 | 43 | rexlimiva | ⊢ ( ∃ 𝑥  ∈  ℤ 𝑏  =  ( 2  ·  𝑥 )  →  ( ∃ 𝑦  ∈  ℤ 𝑎  =  ( 2  ·  𝑦 )  →  ( ( 𝑏  ∈  ℤ  ∧  𝑎  ∈  ℤ )  →  ∃ 𝑧  ∈  ℤ ( 𝑎  +  𝑏 )  =  ( 2  ·  𝑧 ) ) ) ) | 
						
							| 45 | 44 | imp | ⊢ ( ( ∃ 𝑥  ∈  ℤ 𝑏  =  ( 2  ·  𝑥 )  ∧  ∃ 𝑦  ∈  ℤ 𝑎  =  ( 2  ·  𝑦 ) )  →  ( ( 𝑏  ∈  ℤ  ∧  𝑎  ∈  ℤ )  →  ∃ 𝑧  ∈  ℤ ( 𝑎  +  𝑏 )  =  ( 2  ·  𝑧 ) ) ) | 
						
							| 46 |  | oveq2 | ⊢ ( 𝑥  =  𝑧  →  ( 2  ·  𝑥 )  =  ( 2  ·  𝑧 ) ) | 
						
							| 47 | 46 | eqeq2d | ⊢ ( 𝑥  =  𝑧  →  ( ( 𝑎  +  𝑏 )  =  ( 2  ·  𝑥 )  ↔  ( 𝑎  +  𝑏 )  =  ( 2  ·  𝑧 ) ) ) | 
						
							| 48 | 47 | cbvrexvw | ⊢ ( ∃ 𝑥  ∈  ℤ ( 𝑎  +  𝑏 )  =  ( 2  ·  𝑥 )  ↔  ∃ 𝑧  ∈  ℤ ( 𝑎  +  𝑏 )  =  ( 2  ·  𝑧 ) ) | 
						
							| 49 | 45 48 | imbitrrdi | ⊢ ( ( ∃ 𝑥  ∈  ℤ 𝑏  =  ( 2  ·  𝑥 )  ∧  ∃ 𝑦  ∈  ℤ 𝑎  =  ( 2  ·  𝑦 ) )  →  ( ( 𝑏  ∈  ℤ  ∧  𝑎  ∈  ℤ )  →  ∃ 𝑥  ∈  ℤ ( 𝑎  +  𝑏 )  =  ( 2  ·  𝑥 ) ) ) | 
						
							| 50 | 49 | impcom | ⊢ ( ( ( 𝑏  ∈  ℤ  ∧  𝑎  ∈  ℤ )  ∧  ( ∃ 𝑥  ∈  ℤ 𝑏  =  ( 2  ·  𝑥 )  ∧  ∃ 𝑦  ∈  ℤ 𝑎  =  ( 2  ·  𝑦 ) ) )  →  ∃ 𝑥  ∈  ℤ ( 𝑎  +  𝑏 )  =  ( 2  ·  𝑥 ) ) | 
						
							| 51 |  | eqeq1 | ⊢ ( 𝑧  =  ( 𝑎  +  𝑏 )  →  ( 𝑧  =  ( 2  ·  𝑥 )  ↔  ( 𝑎  +  𝑏 )  =  ( 2  ·  𝑥 ) ) ) | 
						
							| 52 | 51 | rexbidv | ⊢ ( 𝑧  =  ( 𝑎  +  𝑏 )  →  ( ∃ 𝑥  ∈  ℤ 𝑧  =  ( 2  ·  𝑥 )  ↔  ∃ 𝑥  ∈  ℤ ( 𝑎  +  𝑏 )  =  ( 2  ·  𝑥 ) ) ) | 
						
							| 53 | 52 1 | elrab2 | ⊢ ( ( 𝑎  +  𝑏 )  ∈  𝐸  ↔  ( ( 𝑎  +  𝑏 )  ∈  ℤ  ∧  ∃ 𝑥  ∈  ℤ ( 𝑎  +  𝑏 )  =  ( 2  ·  𝑥 ) ) ) | 
						
							| 54 | 14 50 53 | sylanbrc | ⊢ ( ( ( 𝑏  ∈  ℤ  ∧  𝑎  ∈  ℤ )  ∧  ( ∃ 𝑥  ∈  ℤ 𝑏  =  ( 2  ·  𝑥 )  ∧  ∃ 𝑦  ∈  ℤ 𝑎  =  ( 2  ·  𝑦 ) ) )  →  ( 𝑎  +  𝑏 )  ∈  𝐸 ) | 
						
							| 55 | 54 | exp32 | ⊢ ( ( 𝑏  ∈  ℤ  ∧  𝑎  ∈  ℤ )  →  ( ∃ 𝑥  ∈  ℤ 𝑏  =  ( 2  ·  𝑥 )  →  ( ∃ 𝑦  ∈  ℤ 𝑎  =  ( 2  ·  𝑦 )  →  ( 𝑎  +  𝑏 )  ∈  𝐸 ) ) ) | 
						
							| 56 | 55 | impancom | ⊢ ( ( 𝑏  ∈  ℤ  ∧  ∃ 𝑥  ∈  ℤ 𝑏  =  ( 2  ·  𝑥 ) )  →  ( 𝑎  ∈  ℤ  →  ( ∃ 𝑦  ∈  ℤ 𝑎  =  ( 2  ·  𝑦 )  →  ( 𝑎  +  𝑏 )  ∈  𝐸 ) ) ) | 
						
							| 57 | 56 | com13 | ⊢ ( ∃ 𝑦  ∈  ℤ 𝑎  =  ( 2  ·  𝑦 )  →  ( 𝑎  ∈  ℤ  →  ( ( 𝑏  ∈  ℤ  ∧  ∃ 𝑥  ∈  ℤ 𝑏  =  ( 2  ·  𝑥 ) )  →  ( 𝑎  +  𝑏 )  ∈  𝐸 ) ) ) | 
						
							| 58 | 11 57 | sylbi | ⊢ ( ∃ 𝑥  ∈  ℤ 𝑎  =  ( 2  ·  𝑥 )  →  ( 𝑎  ∈  ℤ  →  ( ( 𝑏  ∈  ℤ  ∧  ∃ 𝑥  ∈  ℤ 𝑏  =  ( 2  ·  𝑥 ) )  →  ( 𝑎  +  𝑏 )  ∈  𝐸 ) ) ) | 
						
							| 59 | 58 | impcom | ⊢ ( ( 𝑎  ∈  ℤ  ∧  ∃ 𝑥  ∈  ℤ 𝑎  =  ( 2  ·  𝑥 ) )  →  ( ( 𝑏  ∈  ℤ  ∧  ∃ 𝑥  ∈  ℤ 𝑏  =  ( 2  ·  𝑥 ) )  →  ( 𝑎  +  𝑏 )  ∈  𝐸 ) ) | 
						
							| 60 | 59 | imp | ⊢ ( ( ( 𝑎  ∈  ℤ  ∧  ∃ 𝑥  ∈  ℤ 𝑎  =  ( 2  ·  𝑥 ) )  ∧  ( 𝑏  ∈  ℤ  ∧  ∃ 𝑥  ∈  ℤ 𝑏  =  ( 2  ·  𝑥 ) ) )  →  ( 𝑎  +  𝑏 )  ∈  𝐸 ) | 
						
							| 61 | 5 8 60 | syl2anb | ⊢ ( ( 𝑎  ∈  𝐸  ∧  𝑏  ∈  𝐸 )  →  ( 𝑎  +  𝑏 )  ∈  𝐸 ) | 
						
							| 62 | 61 | rgen2 | ⊢ ∀ 𝑎  ∈  𝐸 ∀ 𝑏  ∈  𝐸 ( 𝑎  +  𝑏 )  ∈  𝐸 | 
						
							| 63 |  | 0z | ⊢ 0  ∈  ℤ | 
						
							| 64 |  | 2cn | ⊢ 2  ∈  ℂ | 
						
							| 65 |  | 0zd | ⊢ ( 2  ∈  ℂ  →  0  ∈  ℤ ) | 
						
							| 66 |  | oveq2 | ⊢ ( 𝑥  =  0  →  ( 2  ·  𝑥 )  =  ( 2  ·  0 ) ) | 
						
							| 67 | 66 | eqeq2d | ⊢ ( 𝑥  =  0  →  ( 0  =  ( 2  ·  𝑥 )  ↔  0  =  ( 2  ·  0 ) ) ) | 
						
							| 68 | 67 | adantl | ⊢ ( ( 2  ∈  ℂ  ∧  𝑥  =  0 )  →  ( 0  =  ( 2  ·  𝑥 )  ↔  0  =  ( 2  ·  0 ) ) ) | 
						
							| 69 |  | mul01 | ⊢ ( 2  ∈  ℂ  →  ( 2  ·  0 )  =  0 ) | 
						
							| 70 | 69 | eqcomd | ⊢ ( 2  ∈  ℂ  →  0  =  ( 2  ·  0 ) ) | 
						
							| 71 | 65 68 70 | rspcedvd | ⊢ ( 2  ∈  ℂ  →  ∃ 𝑥  ∈  ℤ 0  =  ( 2  ·  𝑥 ) ) | 
						
							| 72 | 64 71 | ax-mp | ⊢ ∃ 𝑥  ∈  ℤ 0  =  ( 2  ·  𝑥 ) | 
						
							| 73 |  | eqeq1 | ⊢ ( 𝑧  =  0  →  ( 𝑧  =  ( 2  ·  𝑥 )  ↔  0  =  ( 2  ·  𝑥 ) ) ) | 
						
							| 74 | 73 | rexbidv | ⊢ ( 𝑧  =  0  →  ( ∃ 𝑥  ∈  ℤ 𝑧  =  ( 2  ·  𝑥 )  ↔  ∃ 𝑥  ∈  ℤ 0  =  ( 2  ·  𝑥 ) ) ) | 
						
							| 75 | 74 | elrab | ⊢ ( 0  ∈  { 𝑧  ∈  ℤ  ∣  ∃ 𝑥  ∈  ℤ 𝑧  =  ( 2  ·  𝑥 ) }  ↔  ( 0  ∈  ℤ  ∧  ∃ 𝑥  ∈  ℤ 0  =  ( 2  ·  𝑥 ) ) ) | 
						
							| 76 | 63 72 75 | mpbir2an | ⊢ 0  ∈  { 𝑧  ∈  ℤ  ∣  ∃ 𝑥  ∈  ℤ 𝑧  =  ( 2  ·  𝑥 ) } | 
						
							| 77 | 76 1 | eleqtrri | ⊢ 0  ∈  𝐸 | 
						
							| 78 | 1 2 | 2zrngbas | ⊢ 𝐸  =  ( Base ‘ 𝑅 ) | 
						
							| 79 | 1 2 | 2zrngadd | ⊢  +   =  ( +g ‘ 𝑅 ) | 
						
							| 80 | 78 79 | ismgmn0 | ⊢ ( 0  ∈  𝐸  →  ( 𝑅  ∈  Mgm  ↔  ∀ 𝑎  ∈  𝐸 ∀ 𝑏  ∈  𝐸 ( 𝑎  +  𝑏 )  ∈  𝐸 ) ) | 
						
							| 81 | 77 80 | ax-mp | ⊢ ( 𝑅  ∈  Mgm  ↔  ∀ 𝑎  ∈  𝐸 ∀ 𝑏  ∈  𝐸 ( 𝑎  +  𝑏 )  ∈  𝐸 ) | 
						
							| 82 | 62 81 | mpbir | ⊢ 𝑅  ∈  Mgm |