Orthogonal Systems in Vector Spaces over Finite Rings
				
										Keywords:
				
				
																		orthogonal system, 													Erdős–Rényi graphs, 													finite rings															
			
			
										Abstract
We prove that if a subset of the $d$-dimensional vector space over a finite ring is large enough, then the number of $k$-tuples of mutually orthogonal vectors in this set is close to its expected value.