On a solution to the cigarette smoker's problem (without conditional statements)

Abstract

This report discusses a problem first introduced by Patil, who has claimed that the cigarette smoker's problem cannot be solved using the P and V operations introduced by Dijkstra unless conditional statements are used. An examination of Patil's proof shows that he has established this claim only under strong restrictions on the use of P and V . These restrictions eliminate programming techniques used by Dijkstra and others since the first introduction of the semaphore concept. This paper contains a solution to the problem. It also discusses the need for the generalized operators suggested by Patil.