| Step | Hyp | Ref | Expression | 
						
							| 1 |  | oveq2 |  |-  ( N = 0 -> ( X ( ClWWalksNOn ` G ) N ) = ( X ( ClWWalksNOn ` G ) 0 ) ) | 
						
							| 2 |  | clwwlk0on0 |  |-  ( X ( ClWWalksNOn ` G ) 0 ) = (/) | 
						
							| 3 | 1 2 | eqtrdi |  |-  ( N = 0 -> ( X ( ClWWalksNOn ` G ) N ) = (/) ) | 
						
							| 4 | 3 | a1d |  |-  ( N = 0 -> ( -. ( X e. ( Vtx ` G ) /\ N e. NN ) -> ( X ( ClWWalksNOn ` G ) N ) = (/) ) ) | 
						
							| 5 |  | simprl |  |-  ( ( N =/= 0 /\ ( X e. ( Vtx ` G ) /\ N e. NN0 ) ) -> X e. ( Vtx ` G ) ) | 
						
							| 6 |  | elnnne0 |  |-  ( N e. NN <-> ( N e. NN0 /\ N =/= 0 ) ) | 
						
							| 7 | 6 | simplbi2 |  |-  ( N e. NN0 -> ( N =/= 0 -> N e. NN ) ) | 
						
							| 8 | 7 | adantl |  |-  ( ( X e. ( Vtx ` G ) /\ N e. NN0 ) -> ( N =/= 0 -> N e. NN ) ) | 
						
							| 9 | 8 | impcom |  |-  ( ( N =/= 0 /\ ( X e. ( Vtx ` G ) /\ N e. NN0 ) ) -> N e. NN ) | 
						
							| 10 | 5 9 | jca |  |-  ( ( N =/= 0 /\ ( X e. ( Vtx ` G ) /\ N e. NN0 ) ) -> ( X e. ( Vtx ` G ) /\ N e. NN ) ) | 
						
							| 11 | 10 | stoic1a |  |-  ( ( N =/= 0 /\ -. ( X e. ( Vtx ` G ) /\ N e. NN ) ) -> -. ( X e. ( Vtx ` G ) /\ N e. NN0 ) ) | 
						
							| 12 |  | clwwlknonmpo |  |-  ( ClWWalksNOn ` G ) = ( v e. ( Vtx ` G ) , n e. NN0 |-> { w e. ( n ClWWalksN G ) | ( w ` 0 ) = v } ) | 
						
							| 13 | 12 | mpondm0 |  |-  ( -. ( X e. ( Vtx ` G ) /\ N e. NN0 ) -> ( X ( ClWWalksNOn ` G ) N ) = (/) ) | 
						
							| 14 | 11 13 | syl |  |-  ( ( N =/= 0 /\ -. ( X e. ( Vtx ` G ) /\ N e. NN ) ) -> ( X ( ClWWalksNOn ` G ) N ) = (/) ) | 
						
							| 15 | 14 | ex |  |-  ( N =/= 0 -> ( -. ( X e. ( Vtx ` G ) /\ N e. NN ) -> ( X ( ClWWalksNOn ` G ) N ) = (/) ) ) | 
						
							| 16 | 4 15 | pm2.61ine |  |-  ( -. ( X e. ( Vtx ` G ) /\ N e. NN ) -> ( X ( ClWWalksNOn ` G ) N ) = (/) ) |