>>>>>>Q.E.D.
>>>>>
>>>>>Quis erat demonstrandum? (What has been proved?)
>>>>>
>>>>>You accused me of ambiguity in an ambiguous question.
>>>>
>>>>Who has been proved ??
>>>
>>>Hey, my Latin is VERY rusty. I understood that word to be What, Who, Which.
>>
>>Quod erat demonstrandum - what was to be shown.
>
>Sure - "show". But demonstrandum is the infinitive of the verb?
>
>My using Quis was to say "What is it that was to be shown?" Quod is "which" nicht war?

But quis is "who", as in "Quis custodiet ipsos custodes" (who will guard the guardians).