[tmql-wg] tolog 0.1 draft specification

Robert Barta rho@bigpond.net.au
Sat, 12 Apr 2003 09:13:31 +1000

On Fri, Apr 11, 2003 at 06:43:44PM +0200, Lars Marius Garshol wrote:
> | 2.1 Or clauses: Syntax cant be right. '}' is probably wrong.
> What's the problem?

In the (printed) copy from 10-03-2003 Rev 1.7 I had

'{' clauselist ('|' clauselist '}' )+ '}'
It is gone now in


> | 3 : "Query results consist of a list of sets of (variable, value) bindings."
> | 
> |     So : one variable binding is a tuple (var, val)
> |          one match consists of several such tuples
> |          one result is a list of matches
> | 
> |     Right?
> Yes. Should I explain that more clearly, you think?

Well, it is there, but _very_ concise.

> | 4.2. direct-instance-of
> | 
> |     Working with AsTMa! I started to wonder whether there is such
> |     thing as a "direct instance of". Yes, someone can author it, but
> |     who knows what happens over the course of time: New intermediate
> |     topics might be introduced.
> | 
> |     What I am saying is that this concept is not robust. In AsTMa!?
> |     I have not allowed to base queries on it.
> I'm not sure what your concern is. We've seen again and again that
> there are cases where you want to query the type-instance associations
> to see which associations are in there, regardless of the semantics of
> that specific association.

Sure, type-instance _IS_ important. What I am saying is, that *direct
type-instance* seems to be not robust relative to changing the universe:

Universe1 := |

charlie (gorilla)
bn: Charlie

subclass   : gorilla
superclass : animal

subclass   : african-mountain-gorilla
superclass : gorilla


Querying this universe for "all direct instances of gorilla" gives of
course the match 'charlie'. If I now merge in

universe2 := |

charlie (african-mountain-gorilla)


then adding knowledge may lead to a non-monotonicity: Now "all direct
instances of gorilla" may now render 'charlie' if the processor leaves
all instance-ofs as in

  charlie (african-mountain-gorilla gorilla)

, but it may render nothing if the processor collapses charlie
internally into

  charlie (african-mountain-gorilla)

This behaviour I find rather pathological; therefore I tend to
interpret "instance-of" _always_ transitively (relative to