| Step | Hyp | Ref | Expression | 
						
							| 1 |  | mulgass.b |  |-  B = ( Base ` G ) | 
						
							| 2 |  | mulgass.t |  |-  .x. = ( .g ` G ) | 
						
							| 3 |  | oveq1 |  |-  ( n = 1 -> ( n x. N ) = ( 1 x. N ) ) | 
						
							| 4 | 3 | oveq1d |  |-  ( n = 1 -> ( ( n x. N ) .x. X ) = ( ( 1 x. N ) .x. X ) ) | 
						
							| 5 |  | oveq1 |  |-  ( n = 1 -> ( n .x. ( N .x. X ) ) = ( 1 .x. ( N .x. X ) ) ) | 
						
							| 6 | 4 5 | eqeq12d |  |-  ( n = 1 -> ( ( ( n x. N ) .x. X ) = ( n .x. ( N .x. X ) ) <-> ( ( 1 x. N ) .x. X ) = ( 1 .x. ( N .x. X ) ) ) ) | 
						
							| 7 | 6 | imbi2d |  |-  ( n = 1 -> ( ( ( N e. NN /\ X e. B /\ G e. Smgrp ) -> ( ( n x. N ) .x. X ) = ( n .x. ( N .x. X ) ) ) <-> ( ( N e. NN /\ X e. B /\ G e. Smgrp ) -> ( ( 1 x. N ) .x. X ) = ( 1 .x. ( N .x. X ) ) ) ) ) | 
						
							| 8 |  | oveq1 |  |-  ( n = m -> ( n x. N ) = ( m x. N ) ) | 
						
							| 9 | 8 | oveq1d |  |-  ( n = m -> ( ( n x. N ) .x. X ) = ( ( m x. N ) .x. X ) ) | 
						
							| 10 |  | oveq1 |  |-  ( n = m -> ( n .x. ( N .x. X ) ) = ( m .x. ( N .x. X ) ) ) | 
						
							| 11 | 9 10 | eqeq12d |  |-  ( n = m -> ( ( ( n x. N ) .x. X ) = ( n .x. ( N .x. X ) ) <-> ( ( m x. N ) .x. X ) = ( m .x. ( N .x. X ) ) ) ) | 
						
							| 12 | 11 | imbi2d |  |-  ( n = m -> ( ( ( N e. NN /\ X e. B /\ G e. Smgrp ) -> ( ( n x. N ) .x. X ) = ( n .x. ( N .x. X ) ) ) <-> ( ( N e. NN /\ X e. B /\ G e. Smgrp ) -> ( ( m x. N ) .x. X ) = ( m .x. ( N .x. X ) ) ) ) ) | 
						
							| 13 |  | oveq1 |  |-  ( n = ( m + 1 ) -> ( n x. N ) = ( ( m + 1 ) x. N ) ) | 
						
							| 14 | 13 | oveq1d |  |-  ( n = ( m + 1 ) -> ( ( n x. N ) .x. X ) = ( ( ( m + 1 ) x. N ) .x. X ) ) | 
						
							| 15 |  | oveq1 |  |-  ( n = ( m + 1 ) -> ( n .x. ( N .x. X ) ) = ( ( m + 1 ) .x. ( N .x. X ) ) ) | 
						
							| 16 | 14 15 | eqeq12d |  |-  ( n = ( m + 1 ) -> ( ( ( n x. N ) .x. X ) = ( n .x. ( N .x. X ) ) <-> ( ( ( m + 1 ) x. N ) .x. X ) = ( ( m + 1 ) .x. ( N .x. X ) ) ) ) | 
						
							| 17 | 16 | imbi2d |  |-  ( n = ( m + 1 ) -> ( ( ( N e. NN /\ X e. B /\ G e. Smgrp ) -> ( ( n x. N ) .x. X ) = ( n .x. ( N .x. X ) ) ) <-> ( ( N e. NN /\ X e. B /\ G e. Smgrp ) -> ( ( ( m + 1 ) x. N ) .x. X ) = ( ( m + 1 ) .x. ( N .x. X ) ) ) ) ) | 
						
							| 18 |  | oveq1 |  |-  ( n = M -> ( n x. N ) = ( M x. N ) ) | 
						
							| 19 | 18 | oveq1d |  |-  ( n = M -> ( ( n x. N ) .x. X ) = ( ( M x. N ) .x. X ) ) | 
						
							| 20 |  | oveq1 |  |-  ( n = M -> ( n .x. ( N .x. X ) ) = ( M .x. ( N .x. X ) ) ) | 
						
							| 21 | 19 20 | eqeq12d |  |-  ( n = M -> ( ( ( n x. N ) .x. X ) = ( n .x. ( N .x. X ) ) <-> ( ( M x. N ) .x. X ) = ( M .x. ( N .x. X ) ) ) ) | 
						
							| 22 | 21 | imbi2d |  |-  ( n = M -> ( ( ( N e. NN /\ X e. B /\ G e. Smgrp ) -> ( ( n x. N ) .x. X ) = ( n .x. ( N .x. X ) ) ) <-> ( ( N e. NN /\ X e. B /\ G e. Smgrp ) -> ( ( M x. N ) .x. X ) = ( M .x. ( N .x. X ) ) ) ) ) | 
						
							| 23 |  | nncn |  |-  ( N e. NN -> N e. CC ) | 
						
							| 24 | 23 | mullidd |  |-  ( N e. NN -> ( 1 x. N ) = N ) | 
						
							| 25 | 24 | 3ad2ant1 |  |-  ( ( N e. NN /\ X e. B /\ G e. Smgrp ) -> ( 1 x. N ) = N ) | 
						
							| 26 | 25 | oveq1d |  |-  ( ( N e. NN /\ X e. B /\ G e. Smgrp ) -> ( ( 1 x. N ) .x. X ) = ( N .x. X ) ) | 
						
							| 27 |  | sgrpmgm |  |-  ( G e. Smgrp -> G e. Mgm ) | 
						
							| 28 | 1 2 | mulgnncl |  |-  ( ( G e. Mgm /\ N e. NN /\ X e. B ) -> ( N .x. X ) e. B ) | 
						
							| 29 | 27 28 | syl3an1 |  |-  ( ( G e. Smgrp /\ N e. NN /\ X e. B ) -> ( N .x. X ) e. B ) | 
						
							| 30 | 29 | 3coml |  |-  ( ( N e. NN /\ X e. B /\ G e. Smgrp ) -> ( N .x. X ) e. B ) | 
						
							| 31 | 1 2 | mulg1 |  |-  ( ( N .x. X ) e. B -> ( 1 .x. ( N .x. X ) ) = ( N .x. X ) ) | 
						
							| 32 | 30 31 | syl |  |-  ( ( N e. NN /\ X e. B /\ G e. Smgrp ) -> ( 1 .x. ( N .x. X ) ) = ( N .x. X ) ) | 
						
							| 33 | 26 32 | eqtr4d |  |-  ( ( N e. NN /\ X e. B /\ G e. Smgrp ) -> ( ( 1 x. N ) .x. X ) = ( 1 .x. ( N .x. X ) ) ) | 
						
							| 34 |  | oveq1 |  |-  ( ( ( m x. N ) .x. X ) = ( m .x. ( N .x. X ) ) -> ( ( ( m x. N ) .x. X ) ( +g ` G ) ( N .x. X ) ) = ( ( m .x. ( N .x. X ) ) ( +g ` G ) ( N .x. X ) ) ) | 
						
							| 35 |  | nncn |  |-  ( m e. NN -> m e. CC ) | 
						
							| 36 | 35 | adantr |  |-  ( ( m e. NN /\ ( N e. NN /\ X e. B /\ G e. Smgrp ) ) -> m e. CC ) | 
						
							| 37 |  | simpr1 |  |-  ( ( m e. NN /\ ( N e. NN /\ X e. B /\ G e. Smgrp ) ) -> N e. NN ) | 
						
							| 38 | 37 | nncnd |  |-  ( ( m e. NN /\ ( N e. NN /\ X e. B /\ G e. Smgrp ) ) -> N e. CC ) | 
						
							| 39 | 36 38 | adddirp1d |  |-  ( ( m e. NN /\ ( N e. NN /\ X e. B /\ G e. Smgrp ) ) -> ( ( m + 1 ) x. N ) = ( ( m x. N ) + N ) ) | 
						
							| 40 | 39 | oveq1d |  |-  ( ( m e. NN /\ ( N e. NN /\ X e. B /\ G e. Smgrp ) ) -> ( ( ( m + 1 ) x. N ) .x. X ) = ( ( ( m x. N ) + N ) .x. X ) ) | 
						
							| 41 |  | simpr3 |  |-  ( ( m e. NN /\ ( N e. NN /\ X e. B /\ G e. Smgrp ) ) -> G e. Smgrp ) | 
						
							| 42 |  | nnmulcl |  |-  ( ( m e. NN /\ N e. NN ) -> ( m x. N ) e. NN ) | 
						
							| 43 | 42 | 3ad2antr1 |  |-  ( ( m e. NN /\ ( N e. NN /\ X e. B /\ G e. Smgrp ) ) -> ( m x. N ) e. NN ) | 
						
							| 44 |  | simpr2 |  |-  ( ( m e. NN /\ ( N e. NN /\ X e. B /\ G e. Smgrp ) ) -> X e. B ) | 
						
							| 45 |  | eqid |  |-  ( +g ` G ) = ( +g ` G ) | 
						
							| 46 | 1 2 45 | mulgnndir |  |-  ( ( G e. Smgrp /\ ( ( m x. N ) e. NN /\ N e. NN /\ X e. B ) ) -> ( ( ( m x. N ) + N ) .x. X ) = ( ( ( m x. N ) .x. X ) ( +g ` G ) ( N .x. X ) ) ) | 
						
							| 47 | 41 43 37 44 46 | syl13anc |  |-  ( ( m e. NN /\ ( N e. NN /\ X e. B /\ G e. Smgrp ) ) -> ( ( ( m x. N ) + N ) .x. X ) = ( ( ( m x. N ) .x. X ) ( +g ` G ) ( N .x. X ) ) ) | 
						
							| 48 | 40 47 | eqtrd |  |-  ( ( m e. NN /\ ( N e. NN /\ X e. B /\ G e. Smgrp ) ) -> ( ( ( m + 1 ) x. N ) .x. X ) = ( ( ( m x. N ) .x. X ) ( +g ` G ) ( N .x. X ) ) ) | 
						
							| 49 | 1 2 45 | mulgnnp1 |  |-  ( ( m e. NN /\ ( N .x. X ) e. B ) -> ( ( m + 1 ) .x. ( N .x. X ) ) = ( ( m .x. ( N .x. X ) ) ( +g ` G ) ( N .x. X ) ) ) | 
						
							| 50 | 30 49 | sylan2 |  |-  ( ( m e. NN /\ ( N e. NN /\ X e. B /\ G e. Smgrp ) ) -> ( ( m + 1 ) .x. ( N .x. X ) ) = ( ( m .x. ( N .x. X ) ) ( +g ` G ) ( N .x. X ) ) ) | 
						
							| 51 | 48 50 | eqeq12d |  |-  ( ( m e. NN /\ ( N e. NN /\ X e. B /\ G e. Smgrp ) ) -> ( ( ( ( m + 1 ) x. N ) .x. X ) = ( ( m + 1 ) .x. ( N .x. X ) ) <-> ( ( ( m x. N ) .x. X ) ( +g ` G ) ( N .x. X ) ) = ( ( m .x. ( N .x. X ) ) ( +g ` G ) ( N .x. X ) ) ) ) | 
						
							| 52 | 34 51 | imbitrrid |  |-  ( ( m e. NN /\ ( N e. NN /\ X e. B /\ G e. Smgrp ) ) -> ( ( ( m x. N ) .x. X ) = ( m .x. ( N .x. X ) ) -> ( ( ( m + 1 ) x. N ) .x. X ) = ( ( m + 1 ) .x. ( N .x. X ) ) ) ) | 
						
							| 53 | 52 | ex |  |-  ( m e. NN -> ( ( N e. NN /\ X e. B /\ G e. Smgrp ) -> ( ( ( m x. N ) .x. X ) = ( m .x. ( N .x. X ) ) -> ( ( ( m + 1 ) x. N ) .x. X ) = ( ( m + 1 ) .x. ( N .x. X ) ) ) ) ) | 
						
							| 54 | 53 | a2d |  |-  ( m e. NN -> ( ( ( N e. NN /\ X e. B /\ G e. Smgrp ) -> ( ( m x. N ) .x. X ) = ( m .x. ( N .x. X ) ) ) -> ( ( N e. NN /\ X e. B /\ G e. Smgrp ) -> ( ( ( m + 1 ) x. N ) .x. X ) = ( ( m + 1 ) .x. ( N .x. X ) ) ) ) ) | 
						
							| 55 | 7 12 17 22 33 54 | nnind |  |-  ( M e. NN -> ( ( N e. NN /\ X e. B /\ G e. Smgrp ) -> ( ( M x. N ) .x. X ) = ( M .x. ( N .x. X ) ) ) ) | 
						
							| 56 | 55 | 3expd |  |-  ( M e. NN -> ( N e. NN -> ( X e. B -> ( G e. Smgrp -> ( ( M x. N ) .x. X ) = ( M .x. ( N .x. X ) ) ) ) ) ) | 
						
							| 57 | 56 | com4r |  |-  ( G e. Smgrp -> ( M e. NN -> ( N e. NN -> ( X e. B -> ( ( M x. N ) .x. X ) = ( M .x. ( N .x. X ) ) ) ) ) ) | 
						
							| 58 | 57 | 3imp2 |  |-  ( ( G e. Smgrp /\ ( M e. NN /\ N e. NN /\ X e. B ) ) -> ( ( M x. N ) .x. X ) = ( M .x. ( N .x. X ) ) ) |