Dependency

See also Dependent area

A dependency in project management is a link among project's terminal elements.

There are four kinds of dependencies with respect to ordering terminal elements (in order of decreasing frequency of use):

• Finish to start (FS)
• Finish to finish (FF)
• Start to finish (SF)
• Start to start (SS).

There are three kinds of depencies with respect to the reason for the existence of dependency:

• causal (logical)

It is impossible to edit a text before it is wrtitten

It is illogical to pour concrete before you dig the foundations

• resource constraints

It is logically possible to paint four walls in a room simultaneously but there is only one painter

• discretionary.

Traditional critical path-derived schedules are based only on causal (logical) dependencies. The critical chain method necessitates taking into account resource constaint-derived dependencies as well.

See also: project planning

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In computer science, dependency is a state that one object uses a functionality of another object. This may cause changes on implementation of one object can affect that of another object. Information hiding is a way to eliminate dependency to limit influence of changes and improve moduality.

It also is common in talking about software package management. One software package, in order to work or to be fully functional, may depend on other software packages and thus must be installed also, and their specific versions must be known if backwards compatibility is broken between versions. The Apt package format, as well as some versions of the RPM package format.