What are the unambiguous grammar give a suitable example?
A grammar can be unambiguous if the grammar does not contain ambiguity that means if it does not contain more than one leftmost derivation or more than one rightmost derivation or more than one parse tree for the given input string….Unambiguous grammar will be:
- E → E + T.
- E → T.
- T → T * F.
- T → F.
- F → id.
Can regular grammar be unambiguous?
1 Answer. if a grammar is regular then it will be Context free also [as per chomsky hierarchy] it may be or may be not ambiguous depending on grammar. But it is sure any ambiguous regular grammar can be converted into unambiguous regular grammar.
How do you solve the problem of ambiguous grammar?
Methods To Remove Ambiguity-
- By fixing the grammar.
- By adding grouping rules.
- By using semantics and choosing the parse that makes the most sense.
- By adding the precedence rules or other context sensitive parsing rules.
What is meant by unambiguous grammar?
In computer science, an ambiguous grammar is a context-free grammar for which there exists a string that can have more than one leftmost derivation or parse tree, while an unambiguous grammar is a context-free grammar for which every valid string has a unique leftmost derivation or parse tree.
What is leftmost and rightmost derivation?
Leftmost derivation − A leftmost derivation is obtained by applying production to the leftmost variable in each step. Rightmost derivation − A rightmost derivation is obtained by applying production to the rightmost variable in each step.
Which type of grammar is it’s -> AA A -> AAB?
Discussion Forum
| Que. | Which Type of Grammar is it? S → Aa A → Aab | λ |
|---|---|
| b. | Left Linear |
| c. | None of the mentioned |
| d. | Both of the mentioned |
| Answer:Left Linear |
Are all regular languages unambiguous?
Every regular language is recognized by an unambiguous context-free grammar (take a deterministic automaton which recognises it, and make a production R→tS for every edge Rt→S in the DFA, and R→ϵ for every accepting state R).
How would you recognize unambiguous grammar?
A grammar can be unambiguous, if the grammar does not contain ambiguity. This means if it does not contain more than one left most derivation (LMD) or more than one right most derivation (RMD) or more than one parse tree for the given input string, it is an unambiguous grammar.
What is the difference between ambiguous and unambiguous?
As adjectives the difference between unambiguous and ambiguous. is that unambiguous is clear, and having no uncertainty or ambiguity while ambiguous is open to multiple interpretations.
Which of the following grammar is unambiguous?
A context-free grammar is called unambiguous grammar if there exists one and only one derivation tree or parse tree. 1. In ambiguous grammar, the leftmost and rightmost derivations are not same. In unambiguous grammar, the leftmost and rightmost derivations are same.
What is unambiguous language?
: clearly expressed or understood : not ambiguous.
Is leftmost derivation unique?
A unique leftmost derivation and a unique rightmost derivation exist for all the strings. Leftmost derivation and rightmost derivation represents the same parse tree.
What is the grammar of a regular language?
Every regular language is recognized by an unambiguous context-free grammar (take a deterministic automaton which recognises it, and make a production R → t S for every edge R → t S in the DFA, and R → ϵ for every accepting state R ). On the other hand, the natural “grammar” for a regular language is its regular expression.
Are regular expressions a useful characterisation?
When investigating regular languages, regular expressions are obviously a useful characterisation, not least because they are amenable to nice inductions. On the other hand ambiguity can get in the way of some proofs.
How do you construct regular expressions from a DFA?
There’s a standard construction of a regular expression from a DFA: define an expression R (i,j,k) for the language of strings that take state i to state j of the DFA while using intermediate states that belong only to the subset of states from state 1 to state k, as follows.