Chapter 0: Q3E (page 1)
Which of the following pairs of numbers are relatively prime? Show the calculations that led to your conclusions
Short Answer
(a)The pairsof numbersare relative prime.
(b) The pairs of numbers are not very prime.
Chapter 0: Q3E (page 1)
Which of the following pairs of numbers are relatively prime? Show the calculations that led to your conclusions
(a)The pairsof numbersare relative prime.
(b) The pairs of numbers are not very prime.
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Get started for freeShow that A is decidable iff .
Let . Show that AMBIGCFG is undecidable. (Hint: Use a reduction from PCP. Given an instance
of the Post Correspondence Problem, construct a CFG Gwith the rules
where a1,...,ak are new terminal symbols. Prove that this reduction works.)
Recall, in our discussion of the Church–Turing thesis, that we introduced the language is a polynomial in several variables having an integral root}. We stated, but didn’t prove, thatis undecidable. In this problem, you are to prove a different property of—namely, thatis -hard. A problem is -hard if all problems in are polynomial time reducible to it, even though it may not be initself. So you must show that all problems in are polynomial time reducible to .
A two-dimensional finite automaton (2DIM-DFA) is defined as follows. The input is an rectangle, for any m,n. The squares along the boundary of the rectangle contain the symbol # and the internal squares contain symbols over the input alphabet . The transition function indicates the next state and the new head position (Left, Right, Up, Down). The machine accepts when it enters one of the designated accept states. It rejects if it tries to move off the input rectangle or if it never halts. Two such machines are equivalent if they accept the same rectangles. Consider the problem of determining whether two of these machines are equivalent. Formulate this problem as a language and show that it is undecidable.
a). Let C be a context-free language and R be a regular language. Prove that the languageis context free.
b). Let A= { contains equal numbers of }. Use part to show that A is not a CFL
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