Unformatted text preview: State your proof strategy at the beginning. 4. (6 points) A Japanese restaurant sells a 6piece sushi combo, a 9piece combo, and a 20piece combo. The number of individual pieces of sushi that can be ordered are called sushi numbers , which are of the form: c 1 · 6 + c 2 · 9 + c 3 · 20 where c 1 , c 2 , c 3 ∈ N are the number of 6piece, 9piece, and 20piece combos that are ordered. There are clearly an inﬁnite number of sushi numbers. Prove that there are a ﬁnite number of natural numbers that are not sushi numbers. State your proof strategy at the beginning. 5. (6 points) Recall that two (possibly inﬁnite) sets A and B are deﬁned to be the same size if there is a bijection f : A → B . Show that Z + (positive integers) and Z (integers) have the same size. 6. (0 points) Show that R + (positive reals) and R (reals) have the same size. 1...
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 Fall '07
 YaoyunShi
 Natural number, Bacon number

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