Which of the following problems are decidable?
1) Does a given program ever produce an output?
2) If L is a context-free language, then is L’ (complement of L) also context-free?
3) If L is a regular language, then is L’ also regular?
4) If L is a recursive language, then, is L’ also recursive?

Related MCQs

• Which of the following are decidable ? 1. whether the intersection of two regular language is infinite. 2. whether a give context free language is regular 3. whether two push down automata accept the same language. 4. whether a given grammar is context free
• Which of the following are decidable? I. Whether the intersection of two regular languages is infinite II. Whether a given context-free language is regular III. Whether two push-down automata accept the same language IV. Whether a given grammar is context-free
• In multi-programmed systems, it is advantageous if some programs such as editors and compilers can be shared by several users. Which of the following must be true of multi-programmed systems in order that a single copy of a program can be shared by several users? I. The program is a macro II. The program is recursive III.The program is reentrant
• Let L1 be a recursive language, and let L2 be a recursively enumerable but not a recursive language. Which one of the following is TRUE?
• Let L1 be a regular language, L2 be a deterministic context-free language and L3 a recursively enumerable, but not recursive, language. Which one of the following statements is false?
• Let L1 be a recursive language. Let L2 and L3 be languages that are recursively enumerable but not recursive. Which of the following statements is not necessarily true?
• Consider three decision problems P1, P2 and P3. It is known that P1 is decidable and P2 is undecidable. Which one of the following is TRUE?
• Consider the following decision problems: (P1) Does a given finite state machine accept a given string (P2) Does a given context free grammar generate an infinite number of stings Which of the following statements is true?
• Consider the following two problems on undirected graphs: α: Given G(V,E), does G have an independent set of size |v|—4? β: Given G(V,E), does G have an independent set of size 5? Which one of the following is TRUE?
• The grammar whose productions are <stmt> → if id then <stmt> <stmt> → if id then <stmt> else <stmt> <stmt> → id := id is ambiguous because a) the sentence if a then if b then c:= d has two parse trees b) the left most and right most derivations of the sentence if a then if b then c:= d give rise to different parse trees c) the sentence if a then if b then c:= d else c:= f has more than two parse trees d) the sentence if a then if b then c:= d else c:= f has two parse trees