Tyrrell_McAllister comments on Notion of Preference in Ambient Control - Less Wrong

14 Post author: Vladimir_Nesov 07 October 2010 09:21PM

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Comment author: Vladimir_Nesov 08 October 2010 07:02:22AM 3 points [-]

Definitions can't extend a theory, because they don't give you new theorems.

A conservative extension of a language/theory doesn't introduce new theorems in the old language, but could introduce new theorems that make use of new symbols, although in the case of extension by definitions, all new theorems can also be expressed in the smaller (original) language and would be the theorems of original theory.

Comment author: Tyrrell_McAllister 08 October 2010 05:15:30PM 1 point [-]

Okay, thanks. I didn't know that adding certain kinds of axioms was called "extension by definitions".