There is a high degree of player influence on the game world, and the existence of multiple solutions to problems.

What makes this situation unusual is the existence of tangible solutions and the possibility that they can be widely applied.

This demonstrated the existence of exact radiating solutions to the Einstein field equations.

In fact - the problem of existence and uniqueness of solutions is still not fully resolved, but some recent results are quite promising.

In some cases there may not be a solution at all: the question of existence of solutions must be considered.

In the modern approach, the existence of solutions is obtained most often though the Perron method.

As a result, induced width being 2 is required for strong directional path consistency to guarantee the existence of solutions.

Hilbert symbol (below) discusses how techniques based on the existence of solutions to can be made to work.

This nonlinear equation has some rich properties, especially in terms of existence of unique solutions.

However, this crude analysis falls far short of the much more difficult question of global existence of solutions.