User talk:Nichtich~enwiki/Formal languages

Parsers
 * GLR parser (Masura 1984) can parse nondeterministic and ambiguous grammars (Syntactic ambiguity). The parser returns all matching parse trees.
 * LR parser can only parse deterministic context-free languages (DCFL) (there must be only one parse-tree for each parsed string)
 * LR(1) - can exactely parse DCFL
 * SLR ⊊ LALR ⊊ LR

Grammars
 * Recursively enumerable language (RE = type-0) expressed by unrestricted grammars
 * Recursive language (R) can be decided. RE ⊊ R
 * Context-free grammar (CFG) - can be ambiguous
 * Deterministic context-free grammar (DCFL) with DCFL ⊊ CFG


 * regular languages (REG) with REG ⊊ CFG
 * SLR grammar (SLR)
 * Nested Word language

Equivalences: TAG ~ Head grammar (HG) Linear Indexed grammars ~ Combinatory Categorial Grammars (CCG),

Grammars syntax
 * Backus–Naur Form (BNF) can express exactely CFG: (BNF ~ CFG)
 * Indexed grammar
 * Parsing expression grammar (PEG) - cannot be ambiguous
 * Regular expression (RE) can express exactely R (RE ~ R)
 * Regular expressions with backreferences
 * Regular expressions with ...

Less important or too fuzzy:
 * Phrase structure grammar ~ formal grammar (usually context free)