| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ffn |  |-  ( F : R --> NN0 -> F Fn R ) | 
						
							| 2 |  | dffn4 |  |-  ( F Fn R <-> F : R -onto-> ran F ) | 
						
							| 3 | 1 2 | sylib |  |-  ( F : R --> NN0 -> F : R -onto-> ran F ) | 
						
							| 4 | 3 | ad2antlr |  |-  ( ( ( R e. Fin /\ F : R --> NN0 ) /\ R = (/) ) -> F : R -onto-> ran F ) | 
						
							| 5 |  | foeq2 |  |-  ( R = (/) -> ( F : R -onto-> ran F <-> F : (/) -onto-> ran F ) ) | 
						
							| 6 | 5 | adantl |  |-  ( ( ( R e. Fin /\ F : R --> NN0 ) /\ R = (/) ) -> ( F : R -onto-> ran F <-> F : (/) -onto-> ran F ) ) | 
						
							| 7 | 4 6 | mpbid |  |-  ( ( ( R e. Fin /\ F : R --> NN0 ) /\ R = (/) ) -> F : (/) -onto-> ran F ) | 
						
							| 8 |  | fo00 |  |-  ( F : (/) -onto-> ran F <-> ( F = (/) /\ ran F = (/) ) ) | 
						
							| 9 | 8 | simplbi |  |-  ( F : (/) -onto-> ran F -> F = (/) ) | 
						
							| 10 | 7 9 | syl |  |-  ( ( ( R e. Fin /\ F : R --> NN0 ) /\ R = (/) ) -> F = (/) ) | 
						
							| 11 | 10 | oveq2d |  |-  ( ( ( R e. Fin /\ F : R --> NN0 ) /\ R = (/) ) -> ( 0 Ramsey F ) = ( 0 Ramsey (/) ) ) | 
						
							| 12 |  | 0nn0 |  |-  0 e. NN0 | 
						
							| 13 |  | ram0 |  |-  ( 0 e. NN0 -> ( 0 Ramsey (/) ) = 0 ) | 
						
							| 14 | 12 13 | ax-mp |  |-  ( 0 Ramsey (/) ) = 0 | 
						
							| 15 | 14 12 | eqeltri |  |-  ( 0 Ramsey (/) ) e. NN0 | 
						
							| 16 | 11 15 | eqeltrdi |  |-  ( ( ( R e. Fin /\ F : R --> NN0 ) /\ R = (/) ) -> ( 0 Ramsey F ) e. NN0 ) | 
						
							| 17 |  | 0ram2 |  |-  ( ( R e. Fin /\ R =/= (/) /\ F : R --> NN0 ) -> ( 0 Ramsey F ) = sup ( ran F , RR , < ) ) | 
						
							| 18 |  | frn |  |-  ( F : R --> NN0 -> ran F C_ NN0 ) | 
						
							| 19 | 18 | 3ad2ant3 |  |-  ( ( R e. Fin /\ R =/= (/) /\ F : R --> NN0 ) -> ran F C_ NN0 ) | 
						
							| 20 |  | nn0ssz |  |-  NN0 C_ ZZ | 
						
							| 21 | 19 20 | sstrdi |  |-  ( ( R e. Fin /\ R =/= (/) /\ F : R --> NN0 ) -> ran F C_ ZZ ) | 
						
							| 22 |  | fdm |  |-  ( F : R --> NN0 -> dom F = R ) | 
						
							| 23 | 22 | 3ad2ant3 |  |-  ( ( R e. Fin /\ R =/= (/) /\ F : R --> NN0 ) -> dom F = R ) | 
						
							| 24 |  | simp2 |  |-  ( ( R e. Fin /\ R =/= (/) /\ F : R --> NN0 ) -> R =/= (/) ) | 
						
							| 25 | 23 24 | eqnetrd |  |-  ( ( R e. Fin /\ R =/= (/) /\ F : R --> NN0 ) -> dom F =/= (/) ) | 
						
							| 26 |  | dm0rn0 |  |-  ( dom F = (/) <-> ran F = (/) ) | 
						
							| 27 | 26 | necon3bii |  |-  ( dom F =/= (/) <-> ran F =/= (/) ) | 
						
							| 28 | 25 27 | sylib |  |-  ( ( R e. Fin /\ R =/= (/) /\ F : R --> NN0 ) -> ran F =/= (/) ) | 
						
							| 29 |  | nn0ssre |  |-  NN0 C_ RR | 
						
							| 30 | 19 29 | sstrdi |  |-  ( ( R e. Fin /\ R =/= (/) /\ F : R --> NN0 ) -> ran F C_ RR ) | 
						
							| 31 |  | simp1 |  |-  ( ( R e. Fin /\ R =/= (/) /\ F : R --> NN0 ) -> R e. Fin ) | 
						
							| 32 | 3 | 3ad2ant3 |  |-  ( ( R e. Fin /\ R =/= (/) /\ F : R --> NN0 ) -> F : R -onto-> ran F ) | 
						
							| 33 |  | fofi |  |-  ( ( R e. Fin /\ F : R -onto-> ran F ) -> ran F e. Fin ) | 
						
							| 34 | 31 32 33 | syl2anc |  |-  ( ( R e. Fin /\ R =/= (/) /\ F : R --> NN0 ) -> ran F e. Fin ) | 
						
							| 35 |  | fimaxre |  |-  ( ( ran F C_ RR /\ ran F e. Fin /\ ran F =/= (/) ) -> E. x e. ran F A. y e. ran F y <_ x ) | 
						
							| 36 | 30 34 28 35 | syl3anc |  |-  ( ( R e. Fin /\ R =/= (/) /\ F : R --> NN0 ) -> E. x e. ran F A. y e. ran F y <_ x ) | 
						
							| 37 |  | ssrexv |  |-  ( ran F C_ ZZ -> ( E. x e. ran F A. y e. ran F y <_ x -> E. x e. ZZ A. y e. ran F y <_ x ) ) | 
						
							| 38 | 21 36 37 | sylc |  |-  ( ( R e. Fin /\ R =/= (/) /\ F : R --> NN0 ) -> E. x e. ZZ A. y e. ran F y <_ x ) | 
						
							| 39 |  | suprzcl2 |  |-  ( ( ran F C_ ZZ /\ ran F =/= (/) /\ E. x e. ZZ A. y e. ran F y <_ x ) -> sup ( ran F , RR , < ) e. ran F ) | 
						
							| 40 | 21 28 38 39 | syl3anc |  |-  ( ( R e. Fin /\ R =/= (/) /\ F : R --> NN0 ) -> sup ( ran F , RR , < ) e. ran F ) | 
						
							| 41 | 19 40 | sseldd |  |-  ( ( R e. Fin /\ R =/= (/) /\ F : R --> NN0 ) -> sup ( ran F , RR , < ) e. NN0 ) | 
						
							| 42 | 17 41 | eqeltrd |  |-  ( ( R e. Fin /\ R =/= (/) /\ F : R --> NN0 ) -> ( 0 Ramsey F ) e. NN0 ) | 
						
							| 43 | 42 | 3expa |  |-  ( ( ( R e. Fin /\ R =/= (/) ) /\ F : R --> NN0 ) -> ( 0 Ramsey F ) e. NN0 ) | 
						
							| 44 | 43 | an32s |  |-  ( ( ( R e. Fin /\ F : R --> NN0 ) /\ R =/= (/) ) -> ( 0 Ramsey F ) e. NN0 ) | 
						
							| 45 | 16 44 | pm2.61dane |  |-  ( ( R e. Fin /\ F : R --> NN0 ) -> ( 0 Ramsey F ) e. NN0 ) |