CS 541 Lecture -*- Outline -*-

* Logical Computing

	goal: get them to see that some logics correspond to logic programming
		languages, and what properties a language needs to be like that

** What this is about
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	QUESTIONS FOR DESIGNING A
	LOGIC PROGRAMMING LANGUAGE

1. What should the language talk about?

2. What logical connectives work for
   describing things and relationships?

3. What logical connectives work for
   describing queries?

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** What should the language talk about?

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       WHAT TO DESCRIBE/SPECIFY?

What?




Syntax:




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	Q: What should the language talk about?

	... named entities
	    unknown entities
	    relationships

	Give the (lambda) Prolog syntax for these.

	... <lower-case-id> ::= <lower-case-start> <Id-chars>*
	    <Upper-Case-Id> ::= <Upper-Case-Start> <Id-chars>*
	    <term> ::= <lower-case-id> | <term> <atom> | ...
	    <atom> ::= <id> | ( <term> ) | ...

	see the lambda Prolog grammar for more details.

** What logical connectives work for describing relationships?

	motivating question:
		what kinds of logical connectives would work for compuation?

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  CONNECTIVES FOR EFFECTIVE SPECIFICATION

Effectively describe L2?

 - (ordered L2) and (permutation L1 L2)


 - (ordered L2) or (empty L2)



Effectively describe a relationship?

 - (sorted L1 L2) if
    ((ordered L2) and (permutation L1 L2))



 - (less X Y) if not (greater X Y)


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	the key is effectiveness (compuatbility and efficiency of it)

	nondeterminism is ok (define it if needed)

	give real syntax after: and = ","
		or = ";" or is written using separate "clauses".
		implies = "=>" and ":-" in the other direction.

	Q: What about universal quantification?  Existential quantification?

** What logical connectives work for describing conjectures or queries?

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  CONNECTIVES FOR EFFECTIVE QUERYING

Effectively ask for L2?

 - (ordered L2) and (permutation L1 L2)


 - (ordered L2) or (empty L2)


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	I'll let you think about the other connectives and queries in homework.