Formally this approximation is founded on the variational principle, valid for Hamiltonians that are bounded from below.

"It's the economy, stupid" has always been a valid principle.

They sought to discover and to act upon universally valid principles governing humanity, nature, and society.

It is in the high court that the separation-of-powers doctrine must be tested against equally valid constitutional principles.

Despite these facts, most mathematicians accept the axiom of choice as a valid principle for proving new results in mathematics.

The calculated statistical significance of a result is in principle only valid if the hypothesis was specified before any data were examined.

In particular, the law of excluded middle, "A or not A", is not accepted as a valid principle.

Justice can only be a valid principle in the EU if the law, throughout Europe, accords full protection to the weakest members of society.

He carried that valid principle to an extreme, remaining silent on many proper questions.

Mr. Gottschild considers many of Wigman's principles still valid.