Unformatted text preview: M ( x ) accepts, the correct result f ( x ) is written on the output tape when M halts. (On computation paths where M ( x ) does not accept, anything may be written on the output tape.) Answer the following questions: (a) Let f ( G,s,t ) be the function that outputs a path from s to t in directed graph G (or ⊥ if there is no path). Show that f can be computed by a non-deterministic log-space machine. (b) Show that f can be computed by a deterministic machine in space O (log 2 n ). (c) Show that any function that can be computed by a non-deterministic machine in space s ( n ) can be computed by a deterministic machine in space O ( s ( n ) 2 ). 5. Barak-Arora, Exercise 4.5. ( Hint : reduce 2SAT to conn .) 1...
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- Fall '08
- Glossary of graph theory, Non-deterministic Turing machines, Professor Jonathan Katz