| Step | Hyp | Ref | Expression | 
						
							| 1 |  | elfzo0 |  |-  ( I e. ( 0 ..^ N ) <-> ( I e. NN0 /\ N e. NN /\ I < N ) ) | 
						
							| 2 |  | elfzo0 |  |-  ( J e. ( 0 ..^ N ) <-> ( J e. NN0 /\ N e. NN /\ J < N ) ) | 
						
							| 3 |  | nn0re |  |-  ( I e. NN0 -> I e. RR ) | 
						
							| 4 | 3 | adantr |  |-  ( ( I e. NN0 /\ I < N ) -> I e. RR ) | 
						
							| 5 |  | nnre |  |-  ( N e. NN -> N e. RR ) | 
						
							| 6 |  | nn0re |  |-  ( J e. NN0 -> J e. RR ) | 
						
							| 7 |  | resubcl |  |-  ( ( N e. RR /\ J e. RR ) -> ( N - J ) e. RR ) | 
						
							| 8 | 5 6 7 | syl2an |  |-  ( ( N e. NN /\ J e. NN0 ) -> ( N - J ) e. RR ) | 
						
							| 9 | 8 | ancoms |  |-  ( ( J e. NN0 /\ N e. NN ) -> ( N - J ) e. RR ) | 
						
							| 10 | 9 | 3adant3 |  |-  ( ( J e. NN0 /\ N e. NN /\ J < N ) -> ( N - J ) e. RR ) | 
						
							| 11 | 4 10 | anim12i |  |-  ( ( ( I e. NN0 /\ I < N ) /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> ( I e. RR /\ ( N - J ) e. RR ) ) | 
						
							| 12 |  | nn0ge0 |  |-  ( I e. NN0 -> 0 <_ I ) | 
						
							| 13 | 12 | adantr |  |-  ( ( I e. NN0 /\ I < N ) -> 0 <_ I ) | 
						
							| 14 |  | posdif |  |-  ( ( J e. RR /\ N e. RR ) -> ( J < N <-> 0 < ( N - J ) ) ) | 
						
							| 15 | 6 5 14 | syl2an |  |-  ( ( J e. NN0 /\ N e. NN ) -> ( J < N <-> 0 < ( N - J ) ) ) | 
						
							| 16 | 15 | biimp3a |  |-  ( ( J e. NN0 /\ N e. NN /\ J < N ) -> 0 < ( N - J ) ) | 
						
							| 17 | 13 16 | anim12i |  |-  ( ( ( I e. NN0 /\ I < N ) /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> ( 0 <_ I /\ 0 < ( N - J ) ) ) | 
						
							| 18 |  | addgegt0 |  |-  ( ( ( I e. RR /\ ( N - J ) e. RR ) /\ ( 0 <_ I /\ 0 < ( N - J ) ) ) -> 0 < ( I + ( N - J ) ) ) | 
						
							| 19 | 11 17 18 | syl2anc |  |-  ( ( ( I e. NN0 /\ I < N ) /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> 0 < ( I + ( N - J ) ) ) | 
						
							| 20 |  | nn0cn |  |-  ( I e. NN0 -> I e. CC ) | 
						
							| 21 | 20 | adantr |  |-  ( ( I e. NN0 /\ I < N ) -> I e. CC ) | 
						
							| 22 | 21 | adantr |  |-  ( ( ( I e. NN0 /\ I < N ) /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> I e. CC ) | 
						
							| 23 |  | nn0cn |  |-  ( J e. NN0 -> J e. CC ) | 
						
							| 24 | 23 | 3ad2ant1 |  |-  ( ( J e. NN0 /\ N e. NN /\ J < N ) -> J e. CC ) | 
						
							| 25 | 24 | adantl |  |-  ( ( ( I e. NN0 /\ I < N ) /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> J e. CC ) | 
						
							| 26 |  | nncn |  |-  ( N e. NN -> N e. CC ) | 
						
							| 27 | 26 | 3ad2ant2 |  |-  ( ( J e. NN0 /\ N e. NN /\ J < N ) -> N e. CC ) | 
						
							| 28 | 27 | adantl |  |-  ( ( ( I e. NN0 /\ I < N ) /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> N e. CC ) | 
						
							| 29 | 22 25 28 | subadd23d |  |-  ( ( ( I e. NN0 /\ I < N ) /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> ( ( I - J ) + N ) = ( I + ( N - J ) ) ) | 
						
							| 30 | 19 29 | breqtrrd |  |-  ( ( ( I e. NN0 /\ I < N ) /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> 0 < ( ( I - J ) + N ) ) | 
						
							| 31 | 6 | 3ad2ant1 |  |-  ( ( J e. NN0 /\ N e. NN /\ J < N ) -> J e. RR ) | 
						
							| 32 |  | resubcl |  |-  ( ( I e. RR /\ J e. RR ) -> ( I - J ) e. RR ) | 
						
							| 33 | 4 31 32 | syl2an |  |-  ( ( ( I e. NN0 /\ I < N ) /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> ( I - J ) e. RR ) | 
						
							| 34 | 5 | 3ad2ant2 |  |-  ( ( J e. NN0 /\ N e. NN /\ J < N ) -> N e. RR ) | 
						
							| 35 | 34 | adantl |  |-  ( ( ( I e. NN0 /\ I < N ) /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> N e. RR ) | 
						
							| 36 | 33 35 | possumd |  |-  ( ( ( I e. NN0 /\ I < N ) /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> ( 0 < ( ( I - J ) + N ) <-> -u N < ( I - J ) ) ) | 
						
							| 37 | 30 36 | mpbid |  |-  ( ( ( I e. NN0 /\ I < N ) /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> -u N < ( I - J ) ) | 
						
							| 38 | 3 | adantr |  |-  ( ( I e. NN0 /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> I e. RR ) | 
						
							| 39 | 34 | adantl |  |-  ( ( I e. NN0 /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> N e. RR ) | 
						
							| 40 |  | readdcl |  |-  ( ( J e. RR /\ N e. RR ) -> ( J + N ) e. RR ) | 
						
							| 41 | 6 5 40 | syl2an |  |-  ( ( J e. NN0 /\ N e. NN ) -> ( J + N ) e. RR ) | 
						
							| 42 | 41 | 3adant3 |  |-  ( ( J e. NN0 /\ N e. NN /\ J < N ) -> ( J + N ) e. RR ) | 
						
							| 43 | 42 | adantl |  |-  ( ( I e. NN0 /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> ( J + N ) e. RR ) | 
						
							| 44 | 38 39 43 | 3jca |  |-  ( ( I e. NN0 /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> ( I e. RR /\ N e. RR /\ ( J + N ) e. RR ) ) | 
						
							| 45 |  | nn0ge0 |  |-  ( J e. NN0 -> 0 <_ J ) | 
						
							| 46 | 45 | 3ad2ant1 |  |-  ( ( J e. NN0 /\ N e. NN /\ J < N ) -> 0 <_ J ) | 
						
							| 47 | 46 | adantl |  |-  ( ( I e. NN0 /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> 0 <_ J ) | 
						
							| 48 | 5 6 | anim12i |  |-  ( ( N e. NN /\ J e. NN0 ) -> ( N e. RR /\ J e. RR ) ) | 
						
							| 49 | 48 | ancoms |  |-  ( ( J e. NN0 /\ N e. NN ) -> ( N e. RR /\ J e. RR ) ) | 
						
							| 50 | 49 | 3adant3 |  |-  ( ( J e. NN0 /\ N e. NN /\ J < N ) -> ( N e. RR /\ J e. RR ) ) | 
						
							| 51 | 50 | adantl |  |-  ( ( I e. NN0 /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> ( N e. RR /\ J e. RR ) ) | 
						
							| 52 |  | addge02 |  |-  ( ( N e. RR /\ J e. RR ) -> ( 0 <_ J <-> N <_ ( J + N ) ) ) | 
						
							| 53 | 51 52 | syl |  |-  ( ( I e. NN0 /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> ( 0 <_ J <-> N <_ ( J + N ) ) ) | 
						
							| 54 | 47 53 | mpbid |  |-  ( ( I e. NN0 /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> N <_ ( J + N ) ) | 
						
							| 55 | 44 54 | lelttrdi |  |-  ( ( I e. NN0 /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> ( I < N -> I < ( J + N ) ) ) | 
						
							| 56 | 55 | impancom |  |-  ( ( I e. NN0 /\ I < N ) -> ( ( J e. NN0 /\ N e. NN /\ J < N ) -> I < ( J + N ) ) ) | 
						
							| 57 | 56 | imp |  |-  ( ( ( I e. NN0 /\ I < N ) /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> I < ( J + N ) ) | 
						
							| 58 | 4 | adantr |  |-  ( ( ( I e. NN0 /\ I < N ) /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> I e. RR ) | 
						
							| 59 | 31 | adantl |  |-  ( ( ( I e. NN0 /\ I < N ) /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> J e. RR ) | 
						
							| 60 | 58 59 35 | ltsubadd2d |  |-  ( ( ( I e. NN0 /\ I < N ) /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> ( ( I - J ) < N <-> I < ( J + N ) ) ) | 
						
							| 61 | 57 60 | mpbird |  |-  ( ( ( I e. NN0 /\ I < N ) /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> ( I - J ) < N ) | 
						
							| 62 | 37 61 | jca |  |-  ( ( ( I e. NN0 /\ I < N ) /\ ( J e. NN0 /\ N e. NN /\ J < N ) ) -> ( -u N < ( I - J ) /\ ( I - J ) < N ) ) | 
						
							| 63 | 62 | ex |  |-  ( ( I e. NN0 /\ I < N ) -> ( ( J e. NN0 /\ N e. NN /\ J < N ) -> ( -u N < ( I - J ) /\ ( I - J ) < N ) ) ) | 
						
							| 64 | 2 63 | biimtrid |  |-  ( ( I e. NN0 /\ I < N ) -> ( J e. ( 0 ..^ N ) -> ( -u N < ( I - J ) /\ ( I - J ) < N ) ) ) | 
						
							| 65 | 64 | 3adant2 |  |-  ( ( I e. NN0 /\ N e. NN /\ I < N ) -> ( J e. ( 0 ..^ N ) -> ( -u N < ( I - J ) /\ ( I - J ) < N ) ) ) | 
						
							| 66 | 1 65 | sylbi |  |-  ( I e. ( 0 ..^ N ) -> ( J e. ( 0 ..^ N ) -> ( -u N < ( I - J ) /\ ( I - J ) < N ) ) ) | 
						
							| 67 | 66 | imp |  |-  ( ( I e. ( 0 ..^ N ) /\ J e. ( 0 ..^ N ) ) -> ( -u N < ( I - J ) /\ ( I - J ) < N ) ) |