| Step | Hyp | Ref | Expression | 
						
							| 1 |  | brgic | ⊢ ( 𝐺  ≃𝑔  𝐻  ↔  ( 𝐺  GrpIso  𝐻 )  ≠  ∅ ) | 
						
							| 2 |  | n0 | ⊢ ( ( 𝐺  GrpIso  𝐻 )  ≠  ∅  ↔  ∃ 𝑓 𝑓  ∈  ( 𝐺  GrpIso  𝐻 ) ) | 
						
							| 3 |  | gimghm | ⊢ ( 𝑓  ∈  ( 𝐺  GrpIso  𝐻 )  →  𝑓  ∈  ( 𝐺  GrpHom  𝐻 ) ) | 
						
							| 4 |  | eqid | ⊢ ( Base ‘ 𝐺 )  =  ( Base ‘ 𝐺 ) | 
						
							| 5 |  | eqid | ⊢ ( Base ‘ 𝐻 )  =  ( Base ‘ 𝐻 ) | 
						
							| 6 | 4 5 | gimf1o | ⊢ ( 𝑓  ∈  ( 𝐺  GrpIso  𝐻 )  →  𝑓 : ( Base ‘ 𝐺 ) –1-1-onto→ ( Base ‘ 𝐻 ) ) | 
						
							| 7 |  | f1ofo | ⊢ ( 𝑓 : ( Base ‘ 𝐺 ) –1-1-onto→ ( Base ‘ 𝐻 )  →  𝑓 : ( Base ‘ 𝐺 ) –onto→ ( Base ‘ 𝐻 ) ) | 
						
							| 8 | 6 7 | syl | ⊢ ( 𝑓  ∈  ( 𝐺  GrpIso  𝐻 )  →  𝑓 : ( Base ‘ 𝐺 ) –onto→ ( Base ‘ 𝐻 ) ) | 
						
							| 9 | 4 5 | ghmcyg | ⊢ ( ( 𝑓  ∈  ( 𝐺  GrpHom  𝐻 )  ∧  𝑓 : ( Base ‘ 𝐺 ) –onto→ ( Base ‘ 𝐻 ) )  →  ( 𝐺  ∈  CycGrp  →  𝐻  ∈  CycGrp ) ) | 
						
							| 10 | 3 8 9 | syl2anc | ⊢ ( 𝑓  ∈  ( 𝐺  GrpIso  𝐻 )  →  ( 𝐺  ∈  CycGrp  →  𝐻  ∈  CycGrp ) ) | 
						
							| 11 | 10 | exlimiv | ⊢ ( ∃ 𝑓 𝑓  ∈  ( 𝐺  GrpIso  𝐻 )  →  ( 𝐺  ∈  CycGrp  →  𝐻  ∈  CycGrp ) ) | 
						
							| 12 | 2 11 | sylbi | ⊢ ( ( 𝐺  GrpIso  𝐻 )  ≠  ∅  →  ( 𝐺  ∈  CycGrp  →  𝐻  ∈  CycGrp ) ) | 
						
							| 13 | 1 12 | sylbi | ⊢ ( 𝐺  ≃𝑔  𝐻  →  ( 𝐺  ∈  CycGrp  →  𝐻  ∈  CycGrp ) ) |