Re: OT look at my project AlgebraDB :)
Date: 21 Apr 2001 12:22:22 GMT
Message-ID: <987855719.911417_at_cdwork.cvt.stuba.sk>
Jan Hidders <hidders_at_remove.this.win.tue.nl> wrote:
> Since you want to represent your tables in a computer you will have to
> introduce some kind of restriction like 'tables are recursively
> enumerable' or 'recursively decidable'. The question then is what
> operations presever these properties.
Our tables are classic tables which haven't any problem,
infinite tables are built in function like add which have 3 attribute x,y,z
and this table corespond to predicate x+y=z.
so you must deliver to this table at least 2 atributes. for example if you ask
for match for x=5 y=4 z=10 you get answer false.
and next kind of table is defined table, something like equation solving
for example we can define new table "table"
define table{
temp(x,y) project(a,b,x)*add(x,y,z)*result(c,y,z)
table(a,x) temp(x,y)*emp(x,a)
}
any row in this definition is "equation". So we must to solve it.
If there is any recursion we will compute least fix point.
Yes but we must have safe formulas.
At this moment I have allready done about 70 % of it. Try to look at http://algebradb.sourceforge.net/
> Do you know the following article?
> Tirza Hirst and David Harel. Completeness results for recursive data
> bases. Journal of Computer and System Sciences, 52(3):522-536, June
> 1996
No. Is this article on web? Some authors homepage?
Peter Hanusiak
> --
> Jan Hidders
Received on Sat Apr 21 2001 - 14:22:22 CEST