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.
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Question: 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.

Answer: What can not be achieved by ensuring different representations can transformed into each other efficiently?

Question: Passage: Cardiac rehabilitation benefits many who have experienced myocardial infarction, even if there has been substantial heart damage and resultant left ventricular failure; ideally other medical conditions that could interfere with participation should be managed optimally. It should start soon after discharge from hospital. The program may include lifestyle advice, exercise, social support, as well as recommendations about driving, flying, sport participation, stress management, and sexual intercourse.

Answer: Cardiac rehabilitation is not an option under what circumstances?

Question: Passage: Brooke Foss Westcott (18251901) and Fenton J. A. Hort (18281892) published an edition of the New Testament in Greek in 1881. They proposed nine critical rules, including a version of Bengel's rule, "The reading is less likely to be original that shows a disposition to smooth away difficulties." They also argued that "Readings are approved or rejected by reason of the quality, and not the number, of their supporting witnesses", and that "The reading is to be preferred that most fitly explains the existence of the others."

Answer:
When did Westcott and Hort meet?