Category formula - using NOT "@Category[^{name}]"

[DigPeter]

I have set up a category formula as follows:

"@RFolder[file://C:/Users/Peter/Pictures/]" AND "@Keywords|Where|Europe|Spain|Canary Islands" AND ("@Keywords|Taxa|Flowering Plants|Crassulaceae" OR ("@Keywords|Taxa|Flowering Plants|Xanthorrhoeaceae" NOT "@Category[^Asphodelus]" ) OR "@Keywords|Taxa|Flowering Plants|Bromelaceae")

The keyword ending Xanthorrhoeaceae has several leaf keywords, some of which begin with the Asphodelus:  e.g. @Keywords|Taxa|Flowering Plants|Xanthorrhoeaceae|Asphodelus fistulosus.  What I am trying to achieve is to exclude all leaf keywords starting with Asphodelus

This does not work, but it does work if NOT "@Category[^Asphodelus]" is not included.  I have tried placing the NOT clause elsewhere, but without success.

I would be grateful for some guidance please

[DigPeter]

Further to the above:   "@Keywords|Taxa|Flowering Plants|Xanthorrhoeaceae" NOT"@Category[^Asphodelus]" does not work (Asphodelus is not excluded), "@Keywords|Taxa|Flowering Plants|Xanthorrhoeaceae" NOT"@Category[Asphodelus]" does exclude Asphodelus. 

Dropping the '^' in the original formula also works - that is:
"@RFolder[file://C:/Users/Peter/Pictures/]" AND "@Keywords|Where|Europe|Spain|Canary Islands" AND ("@Keywords|Taxa|Flowering Plants|Crassulaceae" OR ("@Keywords|Taxa|Flowering Plants|Xanthorrhoeaceae" NOT "@Category[Asphodelus]" ) OR "@Keywords|Taxa|Flowering Plants|Bromelaceae") .

The formula "@Category[^Asphodelus]" on its own fails to show anything, but "@Category[Asphodelus]" on its own shows all files with leaf keyword starting with Asphodelus

So is '^' redundant?

[ubacher]

This is a related question but not dealing with your problem:

Why a category formula and not just a filter preset?

Do I understand the issue right: Calculated categories need to be frequently updated by the system and thus
will slow the day to day operation? A filter will require you set the right environment (what files to search) and might be slower.

So, unless you need frequent, direct access to the selected files you ought to be better off using a filter.
( Could of course be that a filter can not handle your query!)

[DigPeter]

This is a related question but not dealing with your problem:

Why a category formula and not just a filter preset?

Thanks for your interest.  I am working on a set of images at present and this is the most convenient method of access.

Do I understand the issue right: Calculated categories need to be frequently updated by the system and thus
will slow the day to day operation? A filter will require you set the right environment (what files to search) and might be slower.

I do not know - you might be correct.

So, unless you need frequent, direct access to the selected files you ought to be better off using a filter.
( Could of course be that a filter can not handle your query!)

Fine for one off selections.  But I am not sure that a filter would handle a complex formula like this. 

@Mario  Is this a bug?