Database BASIC LINEAR ALGEBRA Matrices The subalgebras of diagonal and scalar matrices df-scmat  
				
		 
		
			
		 
		Description:   Define the algebra of n x n scalar matrices over a set (usually a ring)
       r, see definition in Connell  p. 57:  "Ascalar matrix  is a diagonal
       matrix for which all the diagonal terms are equal, i.e., a matrix of the
       form cI_n".  (Contributed by AV , 8-Dec-2019) 
		
			
				
					Ref 
					Expression 
				 
				
					Assertion 
					df-scmat   ⊢    ScMat   =    n  ∈  Fin  ,  r  ∈  V  ⟼  ⦋  n   Mat   r /  a ⦌   m  ∈  Base  a |   ∃  c  ∈  Base  r  m  =  c  ⋅  a 1  a              
				 
			
		 
		
				Detailed syntax breakdown 
				
					
						Step 
						Hyp 
						Ref 
						Expression 
					 
						
							0 
								
							 
							cscmat  class   ScMat     
						
							1 
								
							 
							vn  setvar  n    
						
							2 
								
							 
							cfn  class  Fin    
						
							3 
								
							 
							vr  setvar  r    
						
							4 
								
							 
							cvv  class  V    
						
							5 
								1 
							 
							cv  setvar  n    
						
							6 
								
							 
							cmat  class   Mat     
						
							7 
								3 
							 
							cv  setvar  r    
						
							8 
								5  7  6 
							 
							co  class  n   Mat   r    
						
							9 
								
							 
							va  setvar  a    
						
							10 
								
							 
							vm  setvar  m    
						
							11 
								
							 
							cbs  class  Base    
						
							12 
								9 
							 
							cv  setvar  a    
						
							13 
								12  11 
							 
							cfv  class  Base  a    
						
							14 
								
							 
							vc  setvar  c    
						
							15 
								7  11 
							 
							cfv  class  Base  r    
						
							16 
								10 
							 
							cv  setvar  m    
						
							17 
								14 
							 
							cv  setvar  c    
						
							18 
								
							 
							cvsca  class   ⋅  𝑠      
						
							19 
								12  18 
							 
							cfv  class  ⋅  a    
						
							20 
								
							 
							cur  class  1  r    
						
							21 
								12  20 
							 
							cfv  class  1  a    
						
							22 
								17  21  19 
							 
							co  class  c  ⋅  a 1  a    
						
							23 
								16  22 
							 
							wceq  wff   m  =  c  ⋅  a 1  a     
						
							24 
								23  14  15 
							 
							wrex  wff   ∃  c  ∈  Base  r  m  =  c  ⋅  a 1  a       
						
							25 
								24  10  13 
							 
							crab  class   m  ∈  Base  a |   ∃  c  ∈  Base  r  m  =  c  ⋅  a 1  a         
						
							26 
								9  8  25 
							 
							csb  class  ⦋  n   Mat   r /  a ⦌   m  ∈  Base  a |   ∃  c  ∈  Base  r  m  =  c  ⋅  a 1  a         
						
							27 
								1  3  2  4  26 
							 
							cmpo  class    n  ∈  Fin  ,  r  ∈  V  ⟼  ⦋  n   Mat   r /  a ⦌   m  ∈  Base  a |   ∃  c  ∈  Base  r  m  =  c  ⋅  a 1  a           
						
							28 
								0  27 
							 
							wceq  wff    ScMat   =    n  ∈  Fin  ,  r  ∈  V  ⟼  ⦋  n   Mat   r /  a ⦌   m  ∈  Base  a |   ∃  c  ∈  Base  r  m  =  c  ⋅  a 1  a