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CSC 363H               Exercise 1 -- Grading Scheme               Fall 2007
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Mark each question out of 4.  Take off marks for ambiguous/incorrect
notation, ambiguous/vague/incorrect claims that are not substantiated, or
any other aspect of the answer's write-up that makes it difficult or
impossible to understand.

A.  (a) 2 marks: -.5 per mistake
    (c) 2 marks: -.5 per mistake

B.  1 mark:  correct high-level idea
    3 marks: correct details, at the appropriate level

C.  (b) 1 mark:  correct high-level idea
        2 marks: correct details, at the appropriate level

    (c) 1 mark:  correct high-level idea

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Marker's Comments
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In general, students did well.  Because the assignment was pretty easy,
there were no "common" mistakes worth any deep explanation.

A.  Almost everything was correct.

B.  Some of them had an incorrect TM, but in general most of them had nice
    ideas.  Whenever I found mistakes, I challenged them to run their TM on
    specific inputs so that they can realize that it is not correct.

C.  All of them had correct approaches, but also almost all of them made
    one of two mistakes.
    The first mistake is that they did not mark the first cell of the tape,
    however they kept saying that "now we go to the beginning of the tape",
    without understanding that this is somehow superficial.
    The second mistake is that they were inspired by the previous question
    and they assumed that the initial configuration has an empty cell at
    the very left, but without stating that assumption explicitly.
    In both cases I removed .5 marks.