Metamath Proof Explorer
		
		
		
		Description:  Comparable Hilbert lattice elements commute.  Theorem 2.3(iii) of
         Beran p. 40.  (Contributed by NM, 7-Aug-2004)
         (New usage is discouraged.)
		
			
				
					 | 
					 | 
					Ref | 
					Expression | 
				
					
						 | 
						Hypotheses | 
						pjoml2.1 | 
						⊢ 𝐴  ∈   Cℋ   | 
					
					
						 | 
						 | 
						pjoml2.2 | 
						⊢ 𝐵  ∈   Cℋ   | 
					
					
						 | 
						 | 
						lecmi.1 | 
						⊢ 𝐴  ⊆  𝐵  | 
					
				
					 | 
					Assertion | 
					lecmii | 
					⊢  𝐴  𝐶ℋ  𝐵  | 
				
			
		
		
			
				Proof
				
					
						| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							pjoml2.1 | 
							⊢ 𝐴  ∈   Cℋ   | 
						
						
							| 2 | 
							
								
							 | 
							pjoml2.2 | 
							⊢ 𝐵  ∈   Cℋ   | 
						
						
							| 3 | 
							
								
							 | 
							lecmi.1 | 
							⊢ 𝐴  ⊆  𝐵  | 
						
						
							| 4 | 
							
								1 2
							 | 
							lecmi | 
							⊢ ( 𝐴  ⊆  𝐵  →  𝐴  𝐶ℋ  𝐵 )  | 
						
						
							| 5 | 
							
								3 4
							 | 
							ax-mp | 
							⊢ 𝐴  𝐶ℋ  𝐵  |