Triple difference results can be used to estimate unknown variables.

Circuit analysis is the study of methods to solve linear systems for an unknown variable.

An unknown variable is the performance of the Iraqis.

The solution to the power flow problem begins with identifying the known and unknown variables in the system.

The known and unknown variables are dependent on the type of bus.

The problem for Pittsburgh is they have an unknown variable at quarterback.

There were others, too, all of them unknown variables.

Normally, is the unknown variable and will depend on the surrounding surfaces.

The scale for the unknown variable can lie between the other two scales or outside of them.

It is too soon to say anything for sure, because there are still too many unknown variables.