It appears to be a valid model for how human decision-makers make decisions.
We therefore suggest that the Prisoner's Dilemma may not be a valid model where individual variation in payoffs disrupts the essential structure of the game.
A valid model was produced, no matter how bad the "tag soup" supplied had been.
A universal model valid for all laser types does not exist.
However, this conclusion is based on the assumption that current evolutionary theory and intelligent design are the only two valid models to explain life, a false dilemma.
Mosca presented the social structure and methods of governance by the military as a valid model of development for civil society.
This kind of goes against the ethos of a results driven elitism but is probably the more valid epistemological model in the long run.
At the moment we have insufficient data to construct a valid model of how this device operates.
The 110 valid models of driving licence, on the other hand, show Europe as a patchwork quilt.
That model is no longer a valid model for the Commission.