| Step | Hyp | Ref | Expression | 
						
							| 1 |  | simp1 |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) -> N e. NN ) | 
						
							| 2 |  | simp2l |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) -> A e. ( EE ` N ) ) | 
						
							| 3 |  | simp3l |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) -> C e. ( EE ` N ) ) | 
						
							| 4 |  | simp3r |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) -> D e. ( EE ` N ) ) | 
						
							| 5 |  | axsegcon |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ C e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) -> E. x e. ( EE ` N ) ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) ) | 
						
							| 6 | 1 2 3 3 4 5 | syl122anc |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) -> E. x e. ( EE ` N ) ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) ) | 
						
							| 7 | 6 | adantr |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) ) -> E. x e. ( EE ` N ) ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) ) | 
						
							| 8 |  | simprrl |  |-  ( ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) /\ ( ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) /\ ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) ) ) -> C Btwn <. A , x >. ) | 
						
							| 9 |  | simprl1 |  |-  ( ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) /\ ( ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) /\ ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) ) ) -> B =/= C ) | 
						
							| 10 |  | simpl2 |  |-  ( ( ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) /\ ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) ) -> B Btwn <. A , C >. ) | 
						
							| 11 |  | simprl |  |-  ( ( ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) /\ ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) ) -> C Btwn <. A , x >. ) | 
						
							| 12 | 10 11 | jca |  |-  ( ( ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) /\ ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) ) -> ( B Btwn <. A , C >. /\ C Btwn <. A , x >. ) ) | 
						
							| 13 | 12 | adantl |  |-  ( ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) /\ ( ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) /\ ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) ) ) -> ( B Btwn <. A , C >. /\ C Btwn <. A , x >. ) ) | 
						
							| 14 |  | simpl1 |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) -> N e. NN ) | 
						
							| 15 |  | simpl2l |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) -> A e. ( EE ` N ) ) | 
						
							| 16 |  | simpl2r |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) -> B e. ( EE ` N ) ) | 
						
							| 17 |  | simpl3l |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) -> C e. ( EE ` N ) ) | 
						
							| 18 |  | simpr |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) -> x e. ( EE ` N ) ) | 
						
							| 19 |  | btwnexch3 |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ x e. ( EE ` N ) ) ) -> ( ( B Btwn <. A , C >. /\ C Btwn <. A , x >. ) -> C Btwn <. B , x >. ) ) | 
						
							| 20 | 14 15 16 17 18 19 | syl122anc |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) -> ( ( B Btwn <. A , C >. /\ C Btwn <. A , x >. ) -> C Btwn <. B , x >. ) ) | 
						
							| 21 | 20 | adantr |  |-  ( ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) /\ ( ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) /\ ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) ) ) -> ( ( B Btwn <. A , C >. /\ C Btwn <. A , x >. ) -> C Btwn <. B , x >. ) ) | 
						
							| 22 | 13 21 | mpd |  |-  ( ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) /\ ( ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) /\ ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) ) ) -> C Btwn <. B , x >. ) | 
						
							| 23 |  | simprrr |  |-  ( ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) /\ ( ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) /\ ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) ) ) -> <. C , x >. Cgr <. C , D >. ) | 
						
							| 24 | 22 23 | jca |  |-  ( ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) /\ ( ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) /\ ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) ) ) -> ( C Btwn <. B , x >. /\ <. C , x >. Cgr <. C , D >. ) ) | 
						
							| 25 |  | simprl3 |  |-  ( ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) /\ ( ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) /\ ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) ) ) -> C Btwn <. B , D >. ) | 
						
							| 26 |  | simpl3r |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) -> D e. ( EE ` N ) ) | 
						
							| 27 | 14 17 26 | cgrrflxd |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) -> <. C , D >. Cgr <. C , D >. ) | 
						
							| 28 | 27 | adantr |  |-  ( ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) /\ ( ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) /\ ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) ) ) -> <. C , D >. Cgr <. C , D >. ) | 
						
							| 29 | 25 28 | jca |  |-  ( ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) /\ ( ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) /\ ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) ) ) -> ( C Btwn <. B , D >. /\ <. C , D >. Cgr <. C , D >. ) ) | 
						
							| 30 |  | segconeq |  |-  ( ( N e. NN /\ ( C e. ( EE ` N ) /\ C e. ( EE ` N ) /\ D e. ( EE ` N ) ) /\ ( B e. ( EE ` N ) /\ x e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) -> ( ( B =/= C /\ ( C Btwn <. B , x >. /\ <. C , x >. Cgr <. C , D >. ) /\ ( C Btwn <. B , D >. /\ <. C , D >. Cgr <. C , D >. ) ) -> x = D ) ) | 
						
							| 31 | 14 17 17 26 16 18 26 30 | syl133anc |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) -> ( ( B =/= C /\ ( C Btwn <. B , x >. /\ <. C , x >. Cgr <. C , D >. ) /\ ( C Btwn <. B , D >. /\ <. C , D >. Cgr <. C , D >. ) ) -> x = D ) ) | 
						
							| 32 | 31 | adantr |  |-  ( ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) /\ ( ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) /\ ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) ) ) -> ( ( B =/= C /\ ( C Btwn <. B , x >. /\ <. C , x >. Cgr <. C , D >. ) /\ ( C Btwn <. B , D >. /\ <. C , D >. Cgr <. C , D >. ) ) -> x = D ) ) | 
						
							| 33 | 9 24 29 32 | mp3and |  |-  ( ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) /\ ( ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) /\ ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) ) ) -> x = D ) | 
						
							| 34 | 33 | opeq2d |  |-  ( ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) /\ ( ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) /\ ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) ) ) -> <. A , x >. = <. A , D >. ) | 
						
							| 35 | 8 34 | breqtrd |  |-  ( ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) /\ ( ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) /\ ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) ) ) -> C Btwn <. A , D >. ) | 
						
							| 36 | 35 | expr |  |-  ( ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ x e. ( EE ` N ) ) /\ ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) ) -> ( ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) -> C Btwn <. A , D >. ) ) | 
						
							| 37 | 36 | an32s |  |-  ( ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) ) /\ x e. ( EE ` N ) ) -> ( ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) -> C Btwn <. A , D >. ) ) | 
						
							| 38 | 37 | rexlimdva |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) ) -> ( E. x e. ( EE ` N ) ( C Btwn <. A , x >. /\ <. C , x >. Cgr <. C , D >. ) -> C Btwn <. A , D >. ) ) | 
						
							| 39 | 7 38 | mpd |  |-  ( ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) /\ ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) ) -> C Btwn <. A , D >. ) | 
						
							| 40 | 39 | ex |  |-  ( ( N e. NN /\ ( A e. ( EE ` N ) /\ B e. ( EE ` N ) ) /\ ( C e. ( EE ` N ) /\ D e. ( EE ` N ) ) ) -> ( ( B =/= C /\ B Btwn <. A , C >. /\ C Btwn <. B , D >. ) -> C Btwn <. A , D >. ) ) |