| Step | Hyp | Ref | Expression | 
						
							| 1 |  | btwnxfr |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> ( ( B Btwn <. A , C >. /\ <. A , <. B , C >. >. Cgr3 <. D , <. E , F >. >. ) -> E Btwn <. D , F >. ) ) | 
						
							| 2 | 1 | expcomd |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> ( <. A , <. B , C >. >. Cgr3 <. D , <. E , F >. >. -> ( B Btwn <. A , C >. -> E Btwn <. D , F >. ) ) ) | 
						
							| 3 | 2 | imp |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) /\ <. A , <. B , C >. >. Cgr3 <. D , <. E , F >. >. ) -> ( B Btwn <. A , C >. -> E Btwn <. D , F >. ) ) | 
						
							| 4 |  | cgr3permute4 |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> ( <. A , <. B , C >. >. Cgr3 <. D , <. E , F >. >. <-> <. C , <. A , B >. >. Cgr3 <. F , <. D , E >. >. ) ) | 
						
							| 5 |  | biid |  |-  ( N e. NN <-> N e. NN ) | 
						
							| 6 |  | 3anrot |  |-  ( ( C e. ( EE ` N ) /\ A e. ( EE ` N ) /\ B e. ( EE ` N ) ) <-> ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) ) | 
						
							| 7 |  | 3anrot |  |-  ( ( F e. ( EE ` N ) /\ D e. ( EE ` N ) /\ E e. ( EE ` N ) ) <-> ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) | 
						
							| 8 |  | btwnxfr |  |-  ( ( N e. NN /\ ( C e. ( EE ` N ) /\ A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( F e. ( EE ` N ) /\ D e. ( EE ` N ) /\ E e. ( EE ` N ) ) ) -> ( ( A Btwn <. C , B >. /\ <. C , <. A , B >. >. Cgr3 <. F , <. D , E >. >. ) -> D Btwn <. F , E >. ) ) | 
						
							| 9 | 5 6 7 8 | syl3anbr |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> ( ( A Btwn <. C , B >. /\ <. C , <. A , B >. >. Cgr3 <. F , <. D , E >. >. ) -> D Btwn <. F , E >. ) ) | 
						
							| 10 | 9 | expcomd |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> ( <. C , <. A , B >. >. Cgr3 <. F , <. D , E >. >. -> ( A Btwn <. C , B >. -> D Btwn <. F , E >. ) ) ) | 
						
							| 11 | 4 10 | sylbid |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> ( <. A , <. B , C >. >. Cgr3 <. D , <. E , F >. >. -> ( A Btwn <. C , B >. -> D Btwn <. F , E >. ) ) ) | 
						
							| 12 | 11 | imp |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) /\ <. A , <. B , C >. >. Cgr3 <. D , <. E , F >. >. ) -> ( A Btwn <. C , B >. -> D Btwn <. F , E >. ) ) | 
						
							| 13 |  | cgr3permute3 |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> ( <. A , <. B , C >. >. Cgr3 <. D , <. E , F >. >. <-> <. B , <. C , A >. >. Cgr3 <. E , <. F , D >. >. ) ) | 
						
							| 14 |  | 3anrot |  |-  ( ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) <-> ( B e. ( EE ` N ) /\ C e. ( EE ` N ) /\ A e. ( EE ` N ) ) ) | 
						
							| 15 |  | 3anrot |  |-  ( ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) <-> ( E e. ( EE ` N ) /\ F e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) | 
						
							| 16 |  | btwnxfr |  |-  ( ( N e. NN /\ ( B e. ( EE ` N ) /\ C e. ( EE ` N ) /\ A e. ( EE ` N ) ) /\ ( E e. ( EE ` N ) /\ F e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) -> ( ( C Btwn <. B , A >. /\ <. B , <. C , A >. >. Cgr3 <. E , <. F , D >. >. ) -> F Btwn <. E , D >. ) ) | 
						
							| 17 | 5 14 15 16 | syl3anb |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> ( ( C Btwn <. B , A >. /\ <. B , <. C , A >. >. Cgr3 <. E , <. F , D >. >. ) -> F Btwn <. E , D >. ) ) | 
						
							| 18 | 17 | expcomd |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> ( <. B , <. C , A >. >. Cgr3 <. E , <. F , D >. >. -> ( C Btwn <. B , A >. -> F Btwn <. E , D >. ) ) ) | 
						
							| 19 | 13 18 | sylbid |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> ( <. A , <. B , C >. >. Cgr3 <. D , <. E , F >. >. -> ( C Btwn <. B , A >. -> F Btwn <. E , D >. ) ) ) | 
						
							| 20 | 19 | imp |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) /\ <. A , <. B , C >. >. Cgr3 <. D , <. E , F >. >. ) -> ( C Btwn <. B , A >. -> F Btwn <. E , D >. ) ) | 
						
							| 21 | 3 12 20 | 3orim123d |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) /\ <. A , <. B , C >. >. Cgr3 <. D , <. E , F >. >. ) -> ( ( B Btwn <. A , C >. \/ A Btwn <. C , B >. \/ C Btwn <. B , A >. ) -> ( E Btwn <. D , F >. \/ D Btwn <. F , E >. \/ F Btwn <. E , D >. ) ) ) | 
						
							| 22 |  | simp1 |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> N e. NN ) | 
						
							| 23 |  | simp22 |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> B e. ( EE ` N ) ) | 
						
							| 24 |  | simp21 |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> A e. ( EE ` N ) ) | 
						
							| 25 |  | simp23 |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> C e. ( EE ` N ) ) | 
						
							| 26 |  | brcolinear |  |-  ( ( N e. NN /\ ( B e. ( EE ` N ) /\ A e. ( EE ` N ) /\ C e. ( EE ` N ) ) ) -> ( B Colinear <. A , C >. <-> ( B Btwn <. A , C >. \/ A Btwn <. C , B >. \/ C Btwn <. B , A >. ) ) ) | 
						
							| 27 | 22 23 24 25 26 | syl13anc |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> ( B Colinear <. A , C >. <-> ( B Btwn <. A , C >. \/ A Btwn <. C , B >. \/ C Btwn <. B , A >. ) ) ) | 
						
							| 28 | 27 | adantr |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) /\ <. A , <. B , C >. >. Cgr3 <. D , <. E , F >. >. ) -> ( B Colinear <. A , C >. <-> ( B Btwn <. A , C >. \/ A Btwn <. C , B >. \/ C Btwn <. B , A >. ) ) ) | 
						
							| 29 |  | simp32 |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> E e. ( EE ` N ) ) | 
						
							| 30 |  | simp31 |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> D e. ( EE ` N ) ) | 
						
							| 31 |  | simp33 |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> F e. ( EE ` N ) ) | 
						
							| 32 |  | brcolinear |  |-  ( ( N e. NN /\ ( E e. ( EE ` N ) /\ D e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> ( E Colinear <. D , F >. <-> ( E Btwn <. D , F >. \/ D Btwn <. F , E >. \/ F Btwn <. E , D >. ) ) ) | 
						
							| 33 | 22 29 30 31 32 | syl13anc |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> ( E Colinear <. D , F >. <-> ( E Btwn <. D , F >. \/ D Btwn <. F , E >. \/ F Btwn <. E , D >. ) ) ) | 
						
							| 34 | 33 | adantr |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) /\ <. A , <. B , C >. >. Cgr3 <. D , <. E , F >. >. ) -> ( E Colinear <. D , F >. <-> ( E Btwn <. D , F >. \/ D Btwn <. F , E >. \/ F Btwn <. E , D >. ) ) ) | 
						
							| 35 | 21 28 34 | 3imtr4d |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) /\ <. A , <. B , C >. >. Cgr3 <. D , <. E , F >. >. ) -> ( B Colinear <. A , C >. -> E Colinear <. D , F >. ) ) | 
						
							| 36 | 35 | ex |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> ( <. A , <. B , C >. >. Cgr3 <. D , <. E , F >. >. -> ( B Colinear <. A , C >. -> E Colinear <. D , F >. ) ) ) | 
						
							| 37 | 36 | com23 |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> ( B Colinear <. A , C >. -> ( <. A , <. B , C >. >. Cgr3 <. D , <. E , F >. >. -> E Colinear <. D , F >. ) ) ) | 
						
							| 38 | 37 | impd |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( D e. ( EE ` N ) /\ E e. ( EE ` N ) /\ F e. ( EE ` N ) ) ) -> ( ( B Colinear <. A , C >. /\ <. A , <. B , C >. >. Cgr3 <. D , <. E , F >. >. ) -> E Colinear <. D , F >. ) ) |