This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.

Passage: Even though some proofs of complexity-theoretic theorems regularly assume some concrete choice of input encoding, one tries to keep the discussion abstract enough to be independent of the choice of encoding. This can be achieved by ensuring that different representations can be transformed into each other efficiently.
What can not be achieved by ensuring different representations can transformed into each other efficiently?

Passage: After the Peace of Westphalia, several border territories were assigned to the United Provinces. They were federally-governed Generality Lands (Generaliteitslanden). They were Staats-Brabant (present North Brabant), Staats-Vlaanderen (present Zeeuws-Vlaanderen), Staats-Limburg (around Maastricht) and Staats-Oppergelre (around Venlo, after 1715).
In 1715 what was assigned to the United Provinces?

Passage: The first Armenian churches were built between the 4th and 7th century, beginning when Armenia converted to Christianity, and ending with the Arab invasion of Armenia. The early churches were mostly simple basilicas, but some with side apses. By the fifth century the typical cupola cone in the center had become widely used. By the seventh century, centrally planned churches had been built and a more complicated niched buttress and radiating Hrip'simé style had formed. By the time of the Arab invasion, most of what we now know as classical Armenian architecture had formed.

When were the first Arab structures built?