Consider the following identities for regular expressions: (a) (r + s)* = (s + r)* (b) (r*)* = r* (c) (r* s*)* = (r + s)* Which of the above identities are true?

Related MCQs

• Consider the following statements related to compiler construction : I. Lexical Analysis is specified by context-free grammars and implemented by pushdown automata. II. Syntax Analysis is specified by regular expressions and implemented by finite-state machine. Which of the above statement(s) is/are correct?
• Consider the following expression grammar. The seman-tic rules for expression calculation are stated next to each grammar production. E → number E.val = number. val | E '+' E E(1).val = E(2).val + E(3).val | E '×' E E(1).val = E(2).val × E(3).val The above grammar and the semantic rules are fed to a yacc tool (which is an LALR (1) parser generator) for parsing and evaluating arithmetic expressions. Which one of the following is true about the action of yacc for the given grammar?
• Consider the following two statements: P: Every regular grammar is LL(1) Q: Every regular set has a LR(1) grammar Which of the following is TRUE?
• Consider the following grammar. S -> S * E S -> E E -> F + E E -> F F -> id Consider the following LR(0) items corresponding to the grammar above. (i) S -> S * .E (ii) E -> F. + E (iii) E -> F + .E Given the items above, which two of them will appear in the same set in the canonical sets-of-items for the grammar?
• Consider the following expression u*v+a-b*c Which one of the following corresponds to a static single assignment from the above expressions
• Let S and T be language over ={a,b} represented by the regular expressions (a+b*)* and (a+b)*, respectively. Which of the following is true?
• 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?
• 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
• Consider the following Finite State Automaton The language accepted by this automaton is given by the regular expression