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Re: [xml-dev] isXPath1 / isXPath2 -- not(/..)

At 2015-12-19 09:49 -0800, Dimitre Novatchev wrote:
There seems to be something wrong with the type evaluation of Saxon 9.1J

When I evaluate this:

 /.. instance of item()

the result is:

I think that is correct, because /.. evaluates to the empty set, and there are no values in the empty set, so how could the expression be true()?

I get the same with:

() instance of item()

As item() is the root of the type system and every possible value is an item(), the above result means that /.. has type that isn't defined anywhere in the type system.
But /.. isn't a value, it is the empty set ... would item() include the empty set as a value?

I do get true() with

() instance of item()?

And if the empty set were a value that is included in item(), then one couldn't have a sequence type of "item()?".

I hope this is helpful.

. . . . . . . . . Ken

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