But these are actually optimistic assumptions based on what experience the race has had with investigating strange places.

However, the shortages we project would not come close to disappearing even if such optimistic assumptions were to hold.

In making their claims, he said, companies might use optimistic assumptions about, for instance, how often the disk drive is used.

The critics said the plan was based on overly optimistic economic assumptions.

"That's an optimistic assumption that probably won't hold up," he said.

Another possible risk of state tax cuts is that many are based on optimistic economic assumptions.

Even adding in various optimistic assumptions doesn't bring the cost down below $1,000/ton.

In a situation of this kind the optimistic assumption is perilous.

And even with optimistic assumptions, the same will be true for the next 10 years.

Most of the discrepancy is caused by the Administration's having more optimistic economic assumptions.