| Step | Hyp | Ref | Expression | 
						
							| 1 |  | symgfcoeu.g | ⊢ 𝐺  =  ( Base ‘ ( SymGrp ‘ 𝐷 ) ) | 
						
							| 2 |  | eqid | ⊢ ( SymGrp ‘ 𝐷 )  =  ( SymGrp ‘ 𝐷 ) | 
						
							| 3 |  | eqid | ⊢ ( invg ‘ ( SymGrp ‘ 𝐷 ) )  =  ( invg ‘ ( SymGrp ‘ 𝐷 ) ) | 
						
							| 4 | 2 1 3 | symginv | ⊢ ( 𝑃  ∈  𝐺  →  ( ( invg ‘ ( SymGrp ‘ 𝐷 ) ) ‘ 𝑃 )  =  ◡ 𝑃 ) | 
						
							| 5 | 4 | 3ad2ant2 | ⊢ ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  →  ( ( invg ‘ ( SymGrp ‘ 𝐷 ) ) ‘ 𝑃 )  =  ◡ 𝑃 ) | 
						
							| 6 | 2 | symggrp | ⊢ ( 𝐷  ∈  𝑉  →  ( SymGrp ‘ 𝐷 )  ∈  Grp ) | 
						
							| 7 | 6 | 3ad2ant1 | ⊢ ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  →  ( SymGrp ‘ 𝐷 )  ∈  Grp ) | 
						
							| 8 |  | simp2 | ⊢ ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  →  𝑃  ∈  𝐺 ) | 
						
							| 9 | 1 3 | grpinvcl | ⊢ ( ( ( SymGrp ‘ 𝐷 )  ∈  Grp  ∧  𝑃  ∈  𝐺 )  →  ( ( invg ‘ ( SymGrp ‘ 𝐷 ) ) ‘ 𝑃 )  ∈  𝐺 ) | 
						
							| 10 | 7 8 9 | syl2anc | ⊢ ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  →  ( ( invg ‘ ( SymGrp ‘ 𝐷 ) ) ‘ 𝑃 )  ∈  𝐺 ) | 
						
							| 11 | 5 10 | eqeltrrd | ⊢ ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  →  ◡ 𝑃  ∈  𝐺 ) | 
						
							| 12 |  | simp3 | ⊢ ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  →  𝑄  ∈  𝐺 ) | 
						
							| 13 |  | eqid | ⊢ ( +g ‘ ( SymGrp ‘ 𝐷 ) )  =  ( +g ‘ ( SymGrp ‘ 𝐷 ) ) | 
						
							| 14 | 2 1 13 | symgov | ⊢ ( ( ◡ 𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  →  ( ◡ 𝑃 ( +g ‘ ( SymGrp ‘ 𝐷 ) ) 𝑄 )  =  ( ◡ 𝑃  ∘  𝑄 ) ) | 
						
							| 15 | 2 1 13 | symgcl | ⊢ ( ( ◡ 𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  →  ( ◡ 𝑃 ( +g ‘ ( SymGrp ‘ 𝐷 ) ) 𝑄 )  ∈  𝐺 ) | 
						
							| 16 | 14 15 | eqeltrrd | ⊢ ( ( ◡ 𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  →  ( ◡ 𝑃  ∘  𝑄 )  ∈  𝐺 ) | 
						
							| 17 | 11 12 16 | syl2anc | ⊢ ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  →  ( ◡ 𝑃  ∘  𝑄 )  ∈  𝐺 ) | 
						
							| 18 |  | coass | ⊢ ( ( 𝑃  ∘  ◡ 𝑃 )  ∘  𝑄 )  =  ( 𝑃  ∘  ( ◡ 𝑃  ∘  𝑄 ) ) | 
						
							| 19 | 2 1 | symgbasf1o | ⊢ ( 𝑃  ∈  𝐺  →  𝑃 : 𝐷 –1-1-onto→ 𝐷 ) | 
						
							| 20 |  | f1ococnv2 | ⊢ ( 𝑃 : 𝐷 –1-1-onto→ 𝐷  →  ( 𝑃  ∘  ◡ 𝑃 )  =  (  I   ↾  𝐷 ) ) | 
						
							| 21 | 8 19 20 | 3syl | ⊢ ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  →  ( 𝑃  ∘  ◡ 𝑃 )  =  (  I   ↾  𝐷 ) ) | 
						
							| 22 | 21 | coeq1d | ⊢ ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  →  ( ( 𝑃  ∘  ◡ 𝑃 )  ∘  𝑄 )  =  ( (  I   ↾  𝐷 )  ∘  𝑄 ) ) | 
						
							| 23 | 18 22 | eqtr3id | ⊢ ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  →  ( 𝑃  ∘  ( ◡ 𝑃  ∘  𝑄 ) )  =  ( (  I   ↾  𝐷 )  ∘  𝑄 ) ) | 
						
							| 24 | 2 1 | symgbasf1o | ⊢ ( 𝑄  ∈  𝐺  →  𝑄 : 𝐷 –1-1-onto→ 𝐷 ) | 
						
							| 25 |  | f1of | ⊢ ( 𝑄 : 𝐷 –1-1-onto→ 𝐷  →  𝑄 : 𝐷 ⟶ 𝐷 ) | 
						
							| 26 |  | fcoi2 | ⊢ ( 𝑄 : 𝐷 ⟶ 𝐷  →  ( (  I   ↾  𝐷 )  ∘  𝑄 )  =  𝑄 ) | 
						
							| 27 | 12 24 25 26 | 4syl | ⊢ ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  →  ( (  I   ↾  𝐷 )  ∘  𝑄 )  =  𝑄 ) | 
						
							| 28 | 23 27 | eqtr2d | ⊢ ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  →  𝑄  =  ( 𝑃  ∘  ( ◡ 𝑃  ∘  𝑄 ) ) ) | 
						
							| 29 |  | simpr | ⊢ ( ( ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  ∧  𝑝  ∈  𝐺 )  ∧  𝑄  =  ( 𝑃  ∘  𝑝 ) )  →  𝑄  =  ( 𝑃  ∘  𝑝 ) ) | 
						
							| 30 | 29 | coeq2d | ⊢ ( ( ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  ∧  𝑝  ∈  𝐺 )  ∧  𝑄  =  ( 𝑃  ∘  𝑝 ) )  →  ( ◡ 𝑃  ∘  𝑄 )  =  ( ◡ 𝑃  ∘  ( 𝑃  ∘  𝑝 ) ) ) | 
						
							| 31 |  | coass | ⊢ ( ( ◡ 𝑃  ∘  𝑃 )  ∘  𝑝 )  =  ( ◡ 𝑃  ∘  ( 𝑃  ∘  𝑝 ) ) | 
						
							| 32 |  | f1ococnv1 | ⊢ ( 𝑃 : 𝐷 –1-1-onto→ 𝐷  →  ( ◡ 𝑃  ∘  𝑃 )  =  (  I   ↾  𝐷 ) ) | 
						
							| 33 | 8 19 32 | 3syl | ⊢ ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  →  ( ◡ 𝑃  ∘  𝑃 )  =  (  I   ↾  𝐷 ) ) | 
						
							| 34 | 33 | coeq1d | ⊢ ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  →  ( ( ◡ 𝑃  ∘  𝑃 )  ∘  𝑝 )  =  ( (  I   ↾  𝐷 )  ∘  𝑝 ) ) | 
						
							| 35 | 34 | ad2antrr | ⊢ ( ( ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  ∧  𝑝  ∈  𝐺 )  ∧  𝑄  =  ( 𝑃  ∘  𝑝 ) )  →  ( ( ◡ 𝑃  ∘  𝑃 )  ∘  𝑝 )  =  ( (  I   ↾  𝐷 )  ∘  𝑝 ) ) | 
						
							| 36 | 31 35 | eqtr3id | ⊢ ( ( ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  ∧  𝑝  ∈  𝐺 )  ∧  𝑄  =  ( 𝑃  ∘  𝑝 ) )  →  ( ◡ 𝑃  ∘  ( 𝑃  ∘  𝑝 ) )  =  ( (  I   ↾  𝐷 )  ∘  𝑝 ) ) | 
						
							| 37 |  | simplr | ⊢ ( ( ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  ∧  𝑝  ∈  𝐺 )  ∧  𝑄  =  ( 𝑃  ∘  𝑝 ) )  →  𝑝  ∈  𝐺 ) | 
						
							| 38 | 2 1 | symgbasf1o | ⊢ ( 𝑝  ∈  𝐺  →  𝑝 : 𝐷 –1-1-onto→ 𝐷 ) | 
						
							| 39 |  | f1of | ⊢ ( 𝑝 : 𝐷 –1-1-onto→ 𝐷  →  𝑝 : 𝐷 ⟶ 𝐷 ) | 
						
							| 40 |  | fcoi2 | ⊢ ( 𝑝 : 𝐷 ⟶ 𝐷  →  ( (  I   ↾  𝐷 )  ∘  𝑝 )  =  𝑝 ) | 
						
							| 41 | 37 38 39 40 | 4syl | ⊢ ( ( ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  ∧  𝑝  ∈  𝐺 )  ∧  𝑄  =  ( 𝑃  ∘  𝑝 ) )  →  ( (  I   ↾  𝐷 )  ∘  𝑝 )  =  𝑝 ) | 
						
							| 42 | 30 36 41 | 3eqtrrd | ⊢ ( ( ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  ∧  𝑝  ∈  𝐺 )  ∧  𝑄  =  ( 𝑃  ∘  𝑝 ) )  →  𝑝  =  ( ◡ 𝑃  ∘  𝑄 ) ) | 
						
							| 43 | 42 | ex | ⊢ ( ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  ∧  𝑝  ∈  𝐺 )  →  ( 𝑄  =  ( 𝑃  ∘  𝑝 )  →  𝑝  =  ( ◡ 𝑃  ∘  𝑄 ) ) ) | 
						
							| 44 | 43 | ralrimiva | ⊢ ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  →  ∀ 𝑝  ∈  𝐺 ( 𝑄  =  ( 𝑃  ∘  𝑝 )  →  𝑝  =  ( ◡ 𝑃  ∘  𝑄 ) ) ) | 
						
							| 45 |  | coeq2 | ⊢ ( 𝑝  =  ( ◡ 𝑃  ∘  𝑄 )  →  ( 𝑃  ∘  𝑝 )  =  ( 𝑃  ∘  ( ◡ 𝑃  ∘  𝑄 ) ) ) | 
						
							| 46 | 45 | eqeq2d | ⊢ ( 𝑝  =  ( ◡ 𝑃  ∘  𝑄 )  →  ( 𝑄  =  ( 𝑃  ∘  𝑝 )  ↔  𝑄  =  ( 𝑃  ∘  ( ◡ 𝑃  ∘  𝑄 ) ) ) ) | 
						
							| 47 | 46 | eqreu | ⊢ ( ( ( ◡ 𝑃  ∘  𝑄 )  ∈  𝐺  ∧  𝑄  =  ( 𝑃  ∘  ( ◡ 𝑃  ∘  𝑄 ) )  ∧  ∀ 𝑝  ∈  𝐺 ( 𝑄  =  ( 𝑃  ∘  𝑝 )  →  𝑝  =  ( ◡ 𝑃  ∘  𝑄 ) ) )  →  ∃! 𝑝  ∈  𝐺 𝑄  =  ( 𝑃  ∘  𝑝 ) ) | 
						
							| 48 | 17 28 44 47 | syl3anc | ⊢ ( ( 𝐷  ∈  𝑉  ∧  𝑃  ∈  𝐺  ∧  𝑄  ∈  𝐺 )  →  ∃! 𝑝  ∈  𝐺 𝑄  =  ( 𝑃  ∘  𝑝 ) ) |