# Tagged Questions

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### Are constituency grammars and dependency grammars two different types of context free grammars?

From http://en.wikipedia.org/wiki/Parse_tree A concrete syntax tree or parse tree or parsing tree[1] or derivation tree is an ordered, rooted tree that represents the syntactic structure of a ...
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### Weak Precedence Grammar and Parsing

I am studying parsing, i.e. bottom-up parsing. it is said that there some rules which are used by weak precedence grammar. What does weak precedence grammar mean? What about precedence relation? Any ...
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### For regular languages A and B, determine whether B might match early in (A B)

I have two regular languages A and B, and I want to determine whether there is any pair of strings, a in A and b in B, such that (a b) is a prefix of a string in (A B) and the left-most ...
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### Example of a parsing/rewriting system?

I am studying formal languages and playing with writing my own parsers for them. I have a context free grammar parser already that works well. I am wondering if anyone can point me towards actually ...
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### Left-Factoring a grammar into LL(1)

I have a homework assignment where I need to convert a grammar into LL(1). I've already removed the left recursion, but I'm having trouble doing left-factoring. All of the examples I've found are ...
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### What is an IELR(1)-parser?

I try to teach myself the usage of bison. The manpage bison(1) says about bison: Generate a deterministic LR or generalized LR (GLR) parser employing LALR(1), IELR(1), or canonical LR(1) parser ...
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### Is this language LL(1) parseable?

I tried to find a simple example for a language that is not parseable with an LL(1) parser. I finally found this language. $$L=\{a^nb^m|n,m\in\mathbb N\land n\ge m\}$$ Is my hypothesis true or is ...
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### When did $LR(k)$ acquire the meaning “left-to-right scan, rightmost derivation?”

According to the Wikipedia article, the L in $LR(k)$ means "left-to-right scan", and the "R" means "rightmost derivation." However, in Knuth's original paper on $LR(k)$ grammars, he defines $LR(k)$ ...
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### Left recursion and left factoring — which one goes first?

if I have a grammar having a production that contains both left recursion and left factoring like $\qquad \displaystyle F \to FBa \mid cDS \mid c$ which one has priority, left recursion or left ...
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### Are regular expressions $LR(k)$?

If I have a Type 3 Grammar, it can be represented on a pushdown automaton (without doing any operation on the stack) so I can represent regular expressions by using context free languages. But can I ...
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### Computing follow sets conservatively for a PEG grammar

Given a parsing expression grammar (PEG) grammar and the name of the start production, I would like to label each node with the set of characters that can follow it. I would be happy with a good ...
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### Does the language of Regular Expressions need a push down automata to parse it?

I want to convert a user entered regular expression into an NFA so that I can then run the NFA against a string for matching purposes. What is the minimum machine that can be used to parse regular ...
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### Understanding $\text{handle}$ in parsing problem

Originally http://math.stackexchange.com/questions/22614/help-understand-texthandle-in-parsing-problem but unaswered there The BNF is defined as followed: ...