Re: So let me get this right: (Was: NFNF vs 1NF ...)

Paul wrote:
> Jan Hidders wrote:
>

>> There are no theoretical problems with RVA's. Usually they are typed, 
>> which prevent's Russel's paradox, but even if you don't like that, 
>> then you can prevent it by restricting yourself to non-recursive 
>> values, and even if that is too strict for you you can use 
>> non-well-founded sets and still not have any problems with paradoxes.

An untyped RVA is an RVA that can contain any finite or infinite relation.

> I thought that you could only get Russell's paradox if you allowed RVAs
> to be relation variables rather than relation values?

In the original naive set theory in which the paradox was formulated there is no notion of variable, just values.

• Jan Hidders