From: David Carlisle <davidc@nag.co.uk>

Date: Tue, 20 Mar 2012 22:46:34 +0000

Message-ID: <4F6908CA.7040809@nag.co.uk>

CC: "www-math@w3.org" <www-math@w3.org>, Peter Murray-Rust <pm286@cam.ac.uk>

Date: Tue, 20 Mar 2012 22:46:34 +0000

Message-ID: <4F6908CA.7040809@nag.co.uk>

CC: "www-math@w3.org" <www-math@w3.org>, Peter Murray-Rust <pm286@cam.ac.uk>

On 20/03/2012 22:10, Paul Libbrecht wrote: > > Le 20 mars 2012 à 08:12, Andreas Strotmann a écrit : >> >> More to the point, a sequence of assignments would therefore >> 'naturally' be expressed as nested lambda expressions in MathML to >> preserve semantics. >> > > My personal opinion, as a mathematician, is that this way of writing > might be well-founded in terms of expressivity or logic, it remains > fully opaque to most mathematicians except logicians. > > The concept of binding is understandable, and even that of mapping, > but having to enter everything within lambda terms tends to be a real > readability problem. > > paul I'd agree with Paul here. Also, expressing the assignments via lambda binding limits (in most natural encodings) the scope of the assignment to a single expression, which may be too limiting. While Andreas is right that a term encoding like MathML's (or equivalently) OpenMath's has its roots in functional encodings and lambda expressions, I don't see anything wrong with having symbols denoting imperative assignments and, if necessary other imperative constructs. <apply><csymbol>defequal</csymbol><ci>x</ci><cn>1</cm></apply> can be given a perfectly well defined meaning as x := 1 and can be defined to have scope a containing element, or the current math expression, or the entire document, depending on the needs of the application. I came across this old article of Gaston Gonnet on a programming CD for OpenMath http://www.inf.ethz.ch/personal/gonnet/ContDict/Progr.html (The OpenMath examples are written in an old lispish linear syntax pre-dating xml and no longer supported in OpenMath, but the basic ideas are independent of syntax) I was actually looking for this one http://www.openmath.org/cd/prog1.xhtml That encodes assignment as well as for and while loops etc, and is part of the current xml cd collection (although classed as experimental) DavidReceived on Tuesday, 20 March 2012 22:46:59 GMT

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