| Step | Hyp | Ref | Expression | 
						
							| 1 |  | cntzrec.b | ⊢ 𝐵  =  ( Base ‘ 𝑀 ) | 
						
							| 2 |  | cntzrec.z | ⊢ 𝑍  =  ( Cntz ‘ 𝑀 ) | 
						
							| 3 |  | eqid | ⊢ ( +g ‘ 𝑀 )  =  ( +g ‘ 𝑀 ) | 
						
							| 4 | 3 2 | cntzi | ⊢ ( ( 𝑥  ∈  ( 𝑍 ‘ 𝑆 )  ∧  𝑦  ∈  𝑆 )  →  ( 𝑥 ( +g ‘ 𝑀 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝑀 ) 𝑥 ) ) | 
						
							| 5 | 4 | ralrimiva | ⊢ ( 𝑥  ∈  ( 𝑍 ‘ 𝑆 )  →  ∀ 𝑦  ∈  𝑆 ( 𝑥 ( +g ‘ 𝑀 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝑀 ) 𝑥 ) ) | 
						
							| 6 |  | ssralv | ⊢ ( 𝑇  ⊆  𝑆  →  ( ∀ 𝑦  ∈  𝑆 ( 𝑥 ( +g ‘ 𝑀 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝑀 ) 𝑥 )  →  ∀ 𝑦  ∈  𝑇 ( 𝑥 ( +g ‘ 𝑀 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝑀 ) 𝑥 ) ) ) | 
						
							| 7 | 6 | adantl | ⊢ ( ( 𝑆  ⊆  𝐵  ∧  𝑇  ⊆  𝑆 )  →  ( ∀ 𝑦  ∈  𝑆 ( 𝑥 ( +g ‘ 𝑀 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝑀 ) 𝑥 )  →  ∀ 𝑦  ∈  𝑇 ( 𝑥 ( +g ‘ 𝑀 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝑀 ) 𝑥 ) ) ) | 
						
							| 8 | 5 7 | syl5 | ⊢ ( ( 𝑆  ⊆  𝐵  ∧  𝑇  ⊆  𝑆 )  →  ( 𝑥  ∈  ( 𝑍 ‘ 𝑆 )  →  ∀ 𝑦  ∈  𝑇 ( 𝑥 ( +g ‘ 𝑀 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝑀 ) 𝑥 ) ) ) | 
						
							| 9 | 8 | ralrimiv | ⊢ ( ( 𝑆  ⊆  𝐵  ∧  𝑇  ⊆  𝑆 )  →  ∀ 𝑥  ∈  ( 𝑍 ‘ 𝑆 ) ∀ 𝑦  ∈  𝑇 ( 𝑥 ( +g ‘ 𝑀 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝑀 ) 𝑥 ) ) | 
						
							| 10 | 1 2 | cntzssv | ⊢ ( 𝑍 ‘ 𝑆 )  ⊆  𝐵 | 
						
							| 11 |  | sstr | ⊢ ( ( 𝑇  ⊆  𝑆  ∧  𝑆  ⊆  𝐵 )  →  𝑇  ⊆  𝐵 ) | 
						
							| 12 | 11 | ancoms | ⊢ ( ( 𝑆  ⊆  𝐵  ∧  𝑇  ⊆  𝑆 )  →  𝑇  ⊆  𝐵 ) | 
						
							| 13 | 1 3 2 | sscntz | ⊢ ( ( ( 𝑍 ‘ 𝑆 )  ⊆  𝐵  ∧  𝑇  ⊆  𝐵 )  →  ( ( 𝑍 ‘ 𝑆 )  ⊆  ( 𝑍 ‘ 𝑇 )  ↔  ∀ 𝑥  ∈  ( 𝑍 ‘ 𝑆 ) ∀ 𝑦  ∈  𝑇 ( 𝑥 ( +g ‘ 𝑀 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝑀 ) 𝑥 ) ) ) | 
						
							| 14 | 10 12 13 | sylancr | ⊢ ( ( 𝑆  ⊆  𝐵  ∧  𝑇  ⊆  𝑆 )  →  ( ( 𝑍 ‘ 𝑆 )  ⊆  ( 𝑍 ‘ 𝑇 )  ↔  ∀ 𝑥  ∈  ( 𝑍 ‘ 𝑆 ) ∀ 𝑦  ∈  𝑇 ( 𝑥 ( +g ‘ 𝑀 ) 𝑦 )  =  ( 𝑦 ( +g ‘ 𝑀 ) 𝑥 ) ) ) | 
						
							| 15 | 9 14 | mpbird | ⊢ ( ( 𝑆  ⊆  𝐵  ∧  𝑇  ⊆  𝑆 )  →  ( 𝑍 ‘ 𝑆 )  ⊆  ( 𝑍 ‘ 𝑇 ) ) |