What is an ambiguous grammar in compiler design?
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.
Why is ambiguous grammar used?
Grammars are used in compiler construction. Ambiguous grammars are undesirable because the derivation tree provides considerable information about the semantics of a program; conflicting derivation trees provide conflicting information.
What is the problem with ambiguous grammar in compiler design?
Ambiguous grammar is unlikely to be useful for a programming language, because two parse trees structures(or more) for the same string(program) implies two different meanings (executable programs) for the program.
What is the problem of ambiguous grammar?
Since, Ambiguous Grammar has a capability to produce two Parse tress for same expression it’s often confusing for a compiler to figure out which one among all available Parse Trees is the correct one according to the context of the work.
What is ambiguous and unambiguous grammar explain with example?
A context-free grammar is called ambiguous grammar if there exists more than one derivation tree or parse tree. Example – S -> S + S / S * S / S / a. 2. Unambiguous Grammar : A context-free grammar is called unambiguous grammar if there exists one and only one derivation tree or parse tree.
What is ambiguous sentence?
An ambiguous sentence has two or more possible meanings within a single sentence or sequence of words. This can confuse the reader and make the meaning of the sentence unclear.
Can ambiguous grammar be LR K?
An ambiguous grammar can never be LR(k) for any k, because LR(k) algorithm aren’t designed to handle ambiguous grammars. It would get stuck into undecidability problem, if employed upon an ambiguous grammar, no matter how large the constant k is.
How do you handle 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.
How do you solve ambiguous grammar?
What is ambiguous or unambiguous?
A grammar is said to be ambiguous if there exists more than one left most derivation or more than one right most derivation or more than one parse tree for a given input string. If the grammar is not ambiguous then we call unambiguous grammar. If the grammar has ambiguity then it is good for compiler construction.
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.
What is the difference between ambiguous and ambiguous grammar?
A grammar is said to be ambiguous if there exists more than one leftmost derivation or more than one rightmost derivative or more than one parse tree for the given input string. If the grammar is not ambiguous then it is called unambiguous. For the string aabb, the above grammar generates two parse trees:
Is ambiguous grammar bad for compiler construction?
The language generated by an ambiguous grammar is said to be inherently ambiguous. Ambiguity in grammar is not good for a compiler construction.
Would an inherently ambiguous language be suitable as a programming language?
An inherently ambiguous language would be absolutely unsuitable as a programming language, because we would not have any way of fixing a unique structure for all its programs. Disambiguate the grammar i.e., rewriting the grammar such that there is only one derivation or parse tree possible for a string of the language which the grammar represents.
How to remove the ambiguity of a grammar?
Note : Ambiguity of a grammar is undecidable, i.e. there is no particular algorithm for removing the ambiguity of a grammar, but we can remove ambiguity by: Disambiguate the grammar i.e., rewriting the grammar such that there is only one derivation or parse tree possible for a string of the language which the grammar represents.