\begin{definition}[Definition:Desert Crossing Problem]
A '''desert crossing problem''' is one which seeks to find:
:either the maximum distance one may travel through a desert with a specified quantity of fuel
or
:the maximum quantity of resources that one may transport a specified distance across a desert
or
:the most efficient use of resources to cross a desert of a particular width.
In any of these cases the mode of transport may carry a limited quantity of fuel as cargo.
There are various other constraints and conditions which may be applied in particular instances of this problem, for example:
:There may be multiple vehicles available which can be used simultaneously.
:It may or may not be necessary to make the return journey.
:The route may be circular, allowing the resources to be transferred in either direction.
The problem has direct applications in the science of logistics, and is the subject of contemporary research.
\end{definition}