Mon, 28 Jul 2014 17:55:12 -0700 (PDT)

Related articles |
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[2 earlier articles] |

Re: Formatting of Language LRMs ivan@ootbcomp.com (Ivan Godard) (2014-06-20) |

Re: Formatting of Language LRMs gah@ugcs.caltech.edu (glen herrmannsfeldt) (2014-06-21) |

Re: Formatting of Language LRMs kaz@kylheku.com (Kaz Kylheku) (2014-06-21) |

Re: Formatting of Language LRMs Pidgeot18@verizon.net.invalid (=?UTF-8?B?Sm9zaHVhIENyYW5tZXIg8J+Qpw==?=) (2014-06-22) |

Re: Formatting of Language LRMs mertesthomas@gmail.com (2014-06-30) |

Re: Formatting of Language LRMs ivan@ootbcomp.com (Ivan Godard) (2014-07-03) |

Re: Formatting of Language LRMs federation2005@netzero.com (2014-07-28) |

Re: Formatting of Language LRMs federation2005@netzero.com (2014-08-01) |

Re: Formatting of Language LRMs gah@ugcs.caltech.edu (glen herrmannsfeldt) (2014-08-03) |

From: | federation2005@netzero.com |

Newsgroups: | comp.compilers |

Date: | Mon, 28 Jul 2014 17:55:12 -0700 (PDT) |

Organization: | Compilers Central |

References: | 14-06-010 |

Keywords: | syntax |

Posted-Date: | 28 Jul 2014 23:41:55 EDT |

On Tuesday, June 17, 2014 6:24:12 AM UTC-5, Seima Rao wrote:

*> Therefore I am curious to know if there are other interesting formatting*

*> of language standards or language definitions such that the*

*> pattern is different?*

There is one that I've been in the process of developing that

incorporates a unified algebraic framework (actually: a calculus) for

context-free expressions and translation expressions (i.e. upward

revisions of "regular expressions" powerful enough to incorporate

context-free languages and context-free transductions).

There has been much activity as of late in the development and

publication of algebraic frameworks for level 2 in the Chomsky

Hierarchy. An algebra was defined in LNCS 4988 ("The Algebraic

Approach I, II") suitably powerful enough to handle all context-free

subsets of all monoids (even non-free monoids). An equivalent

formalism was devised by Kozen a couple years ago (I believe he calls

them "Continuous Chomsky Algebras"). There is activity underway by an

affiliate in Germany to actually flesh out the equivalence proof.

I'll post more on this or a pointer to an article discussing this,

hopefully in the near future. But here are the basics of what I've

developed:

BNF allows sequences on the RHS of a rule.

EBNF allows regular expressions on the RHS of a rule.

(???) allows full-fledged context-free expressions (CFE) on the RHS.

There are a couple ways one can specify a CFE. One, which harkens to the older

formalism (predating 2008) is the "grammar expressions", consisting of a

series of rules followed by an expression (much like GCC's "statement

expression"). (Even in subexpressions).

The newer notation permits "bra" and "ket" operators in expressions on the

RHS.

It gets interesting past this point ... but again, another time and another

venue.

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