On 25/03/2010 07:51, Heeren, Bastiaan wrote:
> Hello,
>
> I have a silly question about the OpenMath encoding, and the symbols defined 
> in the list1 dictionary in particular. Suppose I want to represent the empty 
> list with the n-ary symbol list1.list. Should that be:
>
>     <OMA><OMS cd='list1' name='list' /></OMA>
>
> or just:
>
>     <OMS cd='list1' name='list' />
>
> In case both are correct, would you consider one to be better than the other 
> one?
>
> I could not figure out the correct encoding from the online documentation. To 
> me, it seems strange to have an application without arguments to the 
> function. On the other hand, if you are expecting a list, it is more regular 
> to have the<OMA>  surrounding the list symbol.
>

You should use the OMA form. That is the list constructor applied to 
form an empty list while the second form is the list constructor itself 
(unapplied) so it is a valid Om expression but it denotes the function 
term rather than the empty list obtained by applying that function to no 
arguments.

David

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