Pattern Ambiguities for Pure Context{free Grammars Pattern Ambiguities for Pure Context{free Grammars Pattern Ambiguities for Pure Context{free Grammars
نویسنده
چکیده
We consider here some special forms of ambiguity for pure context-free grammars, namely pattern avoiding ambiguity, pattern preserving ambiguity, pattern ambiguity, and grammar avoiding ambiguity. The rst two properties are undecidable for arbitrary pure context-free grammars, and in a particular but general enough case we can eeectively decide whether or not a pure context-free grammar is pattern preserving ambiguous.
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