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Re: on alpha conversion

From: David Carlisle <davidc@nag.co.uk>
Date: Tue, 26 May 2009 10:11:13 +0100
Message-Id: <200905260911.n4Q9BD8k003249@edinburgh.nag.co.uk>
To: Andreas.Strotmann@ualberta.ca
Cc: www-math@w3.org



> All I ask is that MathML *continue* to leave variable names untouched so
> that context can reliably refer to them for its own needs - regardless
> how local (as in your example) or global (in mine) that context may
> be.

Andreas, I'm not at all sure what you think has changed here in MathML.
the amount to which MathML changes (or more to the point) doesn't change
variable names has not changed in any draft of MathML as far as I am
aware.

<lambda><bvar><ci>x</ci><bvar><apply><ci>f</ci><ci>x</ci></apply></lambda>

Is fairly unambiguously (in all versions of MathML) the lambda
expression
L x. f(x) and as such it means the same thing as L y. f(y) or just f.
But 
<lambda><bvar><ci>y</ci><bvar><apply><ci>f</ci><ci>y</ci></apply></lambda>
and
<ci>f</ci>

are not the same MathML expression, there is no automatic
lambda-calculus equivalence applied to mathml terms. The only specified
equivalence, other than just literal string identity is the
normalisation of white space.

David



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Received on Tuesday, 26 May 2009 09:11:48 GMT

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