| Step | Hyp | Ref | Expression | 
						
							| 1 |  | rngqiprngfu.r | ⊢ ( 𝜑  →  𝑅  ∈  Rng ) | 
						
							| 2 |  | rngqiprngfu.i | ⊢ ( 𝜑  →  𝐼  ∈  ( 2Ideal ‘ 𝑅 ) ) | 
						
							| 3 |  | rngqiprngfu.j | ⊢ 𝐽  =  ( 𝑅  ↾s  𝐼 ) | 
						
							| 4 |  | rngqiprngfu.u | ⊢ ( 𝜑  →  𝐽  ∈  Ring ) | 
						
							| 5 |  | rngqiprngfu.b | ⊢ 𝐵  =  ( Base ‘ 𝑅 ) | 
						
							| 6 |  | rngqiprngfu.t | ⊢  ·   =  ( .r ‘ 𝑅 ) | 
						
							| 7 |  | rngqiprngfu.1 | ⊢  1   =  ( 1r ‘ 𝐽 ) | 
						
							| 8 |  | rngqiprngfu.g | ⊢  ∼   =  ( 𝑅  ~QG  𝐼 ) | 
						
							| 9 |  | rngqiprngfu.q | ⊢ 𝑄  =  ( 𝑅  /s   ∼  ) | 
						
							| 10 |  | rngqiprngfu.v | ⊢ ( 𝜑  →  𝑄  ∈  Ring ) | 
						
							| 11 |  | rngqiprngfu.e | ⊢ ( 𝜑  →  𝐸  ∈  ( 1r ‘ 𝑄 ) ) | 
						
							| 12 |  | rngqiprngfu.m | ⊢  −   =  ( -g ‘ 𝑅 ) | 
						
							| 13 |  | rngqiprngfu.a | ⊢  +   =  ( +g ‘ 𝑅 ) | 
						
							| 14 |  | rngqiprngfu.n | ⊢ 𝑈  =  ( ( 𝐸  −  (  1   ·  𝐸 ) )  +   1  ) | 
						
							| 15 | 14 | oveq2i | ⊢ (  1   ·  𝑈 )  =  (  1   ·  ( ( 𝐸  −  (  1   ·  𝐸 ) )  +   1  ) ) | 
						
							| 16 | 15 | a1i | ⊢ ( 𝜑  →  (  1   ·  𝑈 )  =  (  1   ·  ( ( 𝐸  −  (  1   ·  𝐸 ) )  +   1  ) ) ) | 
						
							| 17 | 1 2 3 4 5 6 7 | rngqiprng1elbas | ⊢ ( 𝜑  →   1   ∈  𝐵 ) | 
						
							| 18 |  | rnggrp | ⊢ ( 𝑅  ∈  Rng  →  𝑅  ∈  Grp ) | 
						
							| 19 | 1 18 | syl | ⊢ ( 𝜑  →  𝑅  ∈  Grp ) | 
						
							| 20 | 1 2 3 4 5 6 7 8 9 10 11 | rngqiprngfulem2 | ⊢ ( 𝜑  →  𝐸  ∈  𝐵 ) | 
						
							| 21 | 5 6 | rngcl | ⊢ ( ( 𝑅  ∈  Rng  ∧   1   ∈  𝐵  ∧  𝐸  ∈  𝐵 )  →  (  1   ·  𝐸 )  ∈  𝐵 ) | 
						
							| 22 | 1 17 20 21 | syl3anc | ⊢ ( 𝜑  →  (  1   ·  𝐸 )  ∈  𝐵 ) | 
						
							| 23 | 5 12 | grpsubcl | ⊢ ( ( 𝑅  ∈  Grp  ∧  𝐸  ∈  𝐵  ∧  (  1   ·  𝐸 )  ∈  𝐵 )  →  ( 𝐸  −  (  1   ·  𝐸 ) )  ∈  𝐵 ) | 
						
							| 24 | 19 20 22 23 | syl3anc | ⊢ ( 𝜑  →  ( 𝐸  −  (  1   ·  𝐸 ) )  ∈  𝐵 ) | 
						
							| 25 | 5 13 6 | rngdi | ⊢ ( ( 𝑅  ∈  Rng  ∧  (  1   ∈  𝐵  ∧  ( 𝐸  −  (  1   ·  𝐸 ) )  ∈  𝐵  ∧   1   ∈  𝐵 ) )  →  (  1   ·  ( ( 𝐸  −  (  1   ·  𝐸 ) )  +   1  ) )  =  ( (  1   ·  ( 𝐸  −  (  1   ·  𝐸 ) ) )  +  (  1   ·   1  ) ) ) | 
						
							| 26 | 1 17 24 17 25 | syl13anc | ⊢ ( 𝜑  →  (  1   ·  ( ( 𝐸  −  (  1   ·  𝐸 ) )  +   1  ) )  =  ( (  1   ·  ( 𝐸  −  (  1   ·  𝐸 ) ) )  +  (  1   ·   1  ) ) ) | 
						
							| 27 | 5 6 12 1 17 20 22 | rngsubdi | ⊢ ( 𝜑  →  (  1   ·  ( 𝐸  −  (  1   ·  𝐸 ) ) )  =  ( (  1   ·  𝐸 )  −  (  1   ·  (  1   ·  𝐸 ) ) ) ) | 
						
							| 28 | 5 6 | rngass | ⊢ ( ( 𝑅  ∈  Rng  ∧  (  1   ∈  𝐵  ∧   1   ∈  𝐵  ∧  𝐸  ∈  𝐵 ) )  →  ( (  1   ·   1  )  ·  𝐸 )  =  (  1   ·  (  1   ·  𝐸 ) ) ) | 
						
							| 29 | 1 17 17 20 28 | syl13anc | ⊢ ( 𝜑  →  ( (  1   ·   1  )  ·  𝐸 )  =  (  1   ·  (  1   ·  𝐸 ) ) ) | 
						
							| 30 | 3 6 | ressmulr | ⊢ ( 𝐼  ∈  ( 2Ideal ‘ 𝑅 )  →   ·   =  ( .r ‘ 𝐽 ) ) | 
						
							| 31 | 2 30 | syl | ⊢ ( 𝜑  →   ·   =  ( .r ‘ 𝐽 ) ) | 
						
							| 32 | 31 | oveqd | ⊢ ( 𝜑  →  (  1   ·   1  )  =  (  1  ( .r ‘ 𝐽 )  1  ) ) | 
						
							| 33 |  | eqid | ⊢ ( Base ‘ 𝐽 )  =  ( Base ‘ 𝐽 ) | 
						
							| 34 | 33 7 | ringidcl | ⊢ ( 𝐽  ∈  Ring  →   1   ∈  ( Base ‘ 𝐽 ) ) | 
						
							| 35 |  | eqid | ⊢ ( .r ‘ 𝐽 )  =  ( .r ‘ 𝐽 ) | 
						
							| 36 | 33 35 7 | ringlidm | ⊢ ( ( 𝐽  ∈  Ring  ∧   1   ∈  ( Base ‘ 𝐽 ) )  →  (  1  ( .r ‘ 𝐽 )  1  )  =   1  ) | 
						
							| 37 | 4 34 36 | syl2anc2 | ⊢ ( 𝜑  →  (  1  ( .r ‘ 𝐽 )  1  )  =   1  ) | 
						
							| 38 | 32 37 | eqtrd | ⊢ ( 𝜑  →  (  1   ·   1  )  =   1  ) | 
						
							| 39 | 38 | oveq1d | ⊢ ( 𝜑  →  ( (  1   ·   1  )  ·  𝐸 )  =  (  1   ·  𝐸 ) ) | 
						
							| 40 | 29 39 | eqtr3d | ⊢ ( 𝜑  →  (  1   ·  (  1   ·  𝐸 ) )  =  (  1   ·  𝐸 ) ) | 
						
							| 41 | 40 | oveq2d | ⊢ ( 𝜑  →  ( (  1   ·  𝐸 )  −  (  1   ·  (  1   ·  𝐸 ) ) )  =  ( (  1   ·  𝐸 )  −  (  1   ·  𝐸 ) ) ) | 
						
							| 42 |  | eqid | ⊢ ( 0g ‘ 𝑅 )  =  ( 0g ‘ 𝑅 ) | 
						
							| 43 | 5 42 12 | grpsubid | ⊢ ( ( 𝑅  ∈  Grp  ∧  (  1   ·  𝐸 )  ∈  𝐵 )  →  ( (  1   ·  𝐸 )  −  (  1   ·  𝐸 ) )  =  ( 0g ‘ 𝑅 ) ) | 
						
							| 44 | 19 22 43 | syl2anc | ⊢ ( 𝜑  →  ( (  1   ·  𝐸 )  −  (  1   ·  𝐸 ) )  =  ( 0g ‘ 𝑅 ) ) | 
						
							| 45 | 27 41 44 | 3eqtrd | ⊢ ( 𝜑  →  (  1   ·  ( 𝐸  −  (  1   ·  𝐸 ) ) )  =  ( 0g ‘ 𝑅 ) ) | 
						
							| 46 | 45 38 | oveq12d | ⊢ ( 𝜑  →  ( (  1   ·  ( 𝐸  −  (  1   ·  𝐸 ) ) )  +  (  1   ·   1  ) )  =  ( ( 0g ‘ 𝑅 )  +   1  ) ) | 
						
							| 47 | 26 46 | eqtrd | ⊢ ( 𝜑  →  (  1   ·  ( ( 𝐸  −  (  1   ·  𝐸 ) )  +   1  ) )  =  ( ( 0g ‘ 𝑅 )  +   1  ) ) | 
						
							| 48 | 5 13 42 19 17 | grplidd | ⊢ ( 𝜑  →  ( ( 0g ‘ 𝑅 )  +   1  )  =   1  ) | 
						
							| 49 | 16 47 48 | 3eqtrd | ⊢ ( 𝜑  →  (  1   ·  𝑈 )  =   1  ) |