If one needs more than theoretical proof of these conclusions, one need only look to Britain's experience with legalization.

Stewart offered a theoretical proof that this should be the case separately for every selected quality of thermal radiation, but his mathematics was not rigorously valid.

His theoretical proof was and still is considered by some writers to be invalid.

Kirchhoff stated later in 1860 that his theoretical proof was better than Balfour Stewart's, and in some respects it was so.

While lattice computations have suggested that Yang-Mills theory indeed has a mass gap and a tower of excitations, a theoretical proof is still missing.

The theoretical proof for Kirchhoff's universality principle was worked on and debated by various physicists over the same time, and later.

Like a master chef, she added ingredients as they occurred to her, going with a prescient sense bolstered by her theoretical proofs.

In 1991 a theoretical proof was made that a Bose gas can exist in two dimensions.

While the necessity of these adaptations provides practical proof of the grid's inadequacy to serve motorized transport unaided, their introduction made theoretical proof harder.