Problem: Given the question: Extract the answer to the question from the following context. Question: How is the making of a residential elevator compared to full commercial? Context: A residential elevator is often permitted to be of lower cost and complexity than full commercial elevators. They may have unique design characteristics suited for home furnishings, such as hinged wooden shaft-access doors rather than the typical metal sliding doors of commercial elevators. Construction may be less robust than in commercial designs with shorter maintenance periods, but safety systems such as locks on shaft access doors, fall arrestors, and emergency phones must still be present in the event of malfunction.
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The answer is:
less robust


Problem: Given the question: Extract the answer to the question from the following context. Question: What poses an obstacle? Context: The second approach to the problem took as its base the notion of class, and defines a set as a class which belongs to other classes, while a proper class is defined as a class which does not belong to other classes. Under the Zermelo–Fraenkel approach, the axioms impede the construction of a set of all sets which do not belong to themselves. In contrast, under the von Neumann approach, the class of all sets which do not belong to themselves can be constructed, but it is a proper class and not a set.
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The answer is:
the axioms


Problem: Given the question: Extract the answer to the question from the following context. Question: What instructions does the written piece contain? Context: The written score, however, does not usually contain explicit instructions as to how to interpret the piece in terms of production or performance, apart from directions for dynamics, tempo and expression (to a certain extent). This is left to the discretion of the performers, who are guided by their personal experience and musical education, their knowledge of the work's idiom, their personal artistic tastes, and the accumulated body of historic performance practices.
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The answer is:
dynamics, tempo and expression