I think I just realized that years now, I understand wrongly the verbs {tob} and {Daj}. But before I start, just to be on the same page (as americans say), here are the definitions:

tob (v) test conclusively, prove

Daj (v) test inconclusively

Suppose I write the following sentences:

nger vItobpu'

nger vIDajpu'

Years now, I thought that the {nger vItobpu'} means "I proved that the theory is correct", and that the {nger vIDajpu'} means "I proved that the theory is wrong".

But now I realized that the meanings are rather the folllowing:

nger vItobpu'

I tested conclusively the theory

(I say that I tested it thoroughly, but without this meaning that the theory is necessarily correct; after the "testing" finished, perhaps the conclusion was that the theory was perfectly wrong)

nger vIDajpu'

I tested inconclusively the theory

(I just say that I didn't thoroughly test the theory; it may be a valid theory, or it may be a wrong one, but the "testing" wasn't thorough/effective enough to come to definite conclusion)

Is my understanding correct?

Mostly. I think the word prove in the gloss suggests that tob implies not only that the test was conclusive, but that it was also positive. If you tob something, you conclusively show that it is correct. To test something conclusively and show that it is wrong, use tobHa' disprove.

nger vItobpu' I tested the theory and showed conclusively that it is correct.
nger vItobHa'pu' I tested the theory and showed conclusively that it is incorrect.
nger vIDajpu' I tested the theory but was unable to conclusively show its validity.

-- 
SuStel
http://trimboli.name