secondly, when behavioral preferences, and the satisfaction of which is incompatible with another person's implementation of his or her preferences, thirdly, when a party wants some mutually desirable resource that is in short supply, such that the wants of all parties involved may not be satisfied fully. Fourthly, when a party possesses attitudes, values, skills, and goals that are salient in directing his or her behavior but are perceived to be exclusive of the attitudes, values, skills, and goals held by the other(s).
When resources are required to simultaneously make the majority of the active members are not full.