What is Deadlock in Operating System (OS)?

A deadlock is a deadlock condition in a system where a process cannot proceed because it needs to obtain a resource held by another process but it itself is holding a resource that the other process needs.

Resource Allocation Graph (RAG)

It is a directed graph which consists of set of vertices V and a set of edges E. V is divided into set of processes (P) and set of resources (R). E is divided into two types: requesting and allocating edge.