You're missing that != (like the other comparison operators) returns true if
any item on the left is != to any item on the right. You probably want

not(activity = preceding-sibling::Rec/activity)

but I haven't looked at the problem, it might be that you want

 not(activity = preceding-sibling::Rec[1]/activity)

which only looks at the immediately preceding sibling.

Michael Kay
http://www.saxonica.com/

> -----Original Message-----
> From: Ilya Konanykhin [mailto:ilya.konanykhin.ml@xxxxxxxxx] 
> Sent: 14 November 2007 04:01
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject: Re:  Template matching preceding-sibling.
> 
> Hi, list!
> I'm asking for clarification of the topic being on the list 
> several days ago (Nov 8). Steve <subsume@xxxxxxxxx> wrote:
> 
> > I'm missing something fundamental, what is it?
> >
> > <xsl:template match="Rec[activity != 
> preceding-sibling::Rec/activity 
> > or not(preceding-sibling::Rec)]">  Ello xslers.
> > </xsl:template>
> >
> > <xml>
> >    <Rec>
> >      <activity>hi</activity>
> >    </Rec>
> >    <Rec>
> >       <activity>hi</activity>
> >    </Rec>
> > </xml>
> >
> > ----
> >
> > Above should only print anything once, but I'm getting it each time.
> > What am I not getting?
> 
> Charles Knell and Scott Trenda gave advices/made notices, 
> thus confirming, that the problem exists. But copying the 
> input data and the template given by Steve and running it I 
> obtained exactly the result required by him in the first 
> topic-forming message, if I understood his request correctly. 
> I used MSXML (not sure about version, but don't think it's 
> important in this simple
> case) and Saxon 9, for the latter I also tried changing 
> template version to 2.0 - the result stood the same. Data follows:
> 
> -----------
> input.xml:
> <?xml version="1.0"?>
> 
> <xml>
>    <Rec>
>      <activity>hi</activity>
>    </Rec>
>    <Rec>
>       <activity>hi</activity>
>    </Rec>
> </xml>
> 
> -----------
> input.xsl:
> <?xml version="1.0"?>
> 
> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
> version="1.0">
> 
> <xsl:template match="Rec[activity != 
> preceding-sibling::Rec/activity or not(preceding-sibling::Rec)]">
>   Ello xslers.
> </xsl:template>
> 
> </xsl:stylesheet>
> 
> -----------
> output.xml:
> <?xml version="1.0" encoding="UTF-8"?>
> 
>   Ello xslers.
> 
> 
>       hi
> 
> -----------
> 
> As it is clearly seen the string "Ello xslers" appears only 
> once and not twice as Steve wrote ("hi" comes from the defaul 
> copy rules, as I understand it).
> 
> Did I missed or misunderstood something very basic? Can 
> someone please reveal the trick to me (especially interested 
> in Charles' oppinion as he was involved most intensively in 
> the discussion).
> 
> Many thanks in advance,
> Ilya