Article View: comp.lang.misc
Article #6513Re: Expressive Power - What is it ?
From: Ken Johnson
Date: Tue, 30 May 1989 16:55
Date: Tue, 30 May 1989 16:55
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1476 bytes
In article <769@cf-cm.UUCP> ted@computing-maths.cardiff.ac.uk (Ted Lawson) writes: > > Can anyone provide or (preferably) point-to a definition of, > or discussion about, the oft-heard term "Expressive Power" ? > ... If, for every > type, A's type includes B's corresponding type, then A > is more expressive than B (or equally expressive)." No, this doesn't seem to hold water as a complete definition. Suppose that in language A I can form statements of the type S1, S2 and S3. In language B I can form statements of the type S2, S3, S4,S5, ... S100000. Then language B can be said to be more expressive than language A, but language A is handy if I want to execute statements of the form S1. The definition you suggest does not allow for this sort of case. -- Ken Johnson, AI Applications Institute, 80 South Bridge, Edinburgh EH1 1HN E-mail ken@aiai.ed.ac.uk, phone 031-225 4464 extension 212 `I have read your article, Mr. Johnson, and I am no wiser than when I started.' -- `Possibly not, sir, but far better informed.'
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arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!sun-barr!cs.utexas.edu!uunet!mcvax!ukc!etive!aiai!kenReferences:
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!sun-barr!cs.utexas.edu!uunet!mcvax!ukc!etive!aiai!ken From: ken@aiai.ed.ac.uk (Ken Johnson) Newsgroups: comp.lang.misc Subject: Re: Expressive Power - What is it ? Message-ID: <494@skye.ed.ac.uk> Date: 30 May 89 16:55:35 GMT References: <769@cf-cm.UUCP> Reply-To: ken@aiai.UUCP (Ken Johnson) Organization: AIAI, University of Edinburgh, Scotland Lines: 23