Re: Perhaps an idiotic question

paul c <toledobythesea_at_oohay.ac> wrote in news:HJpbh.387015$1T2.248520_at_pd7urf2no:

> But it perplexes me even though I admit I have no good reason for
> asking:
>
> If I declare a relation (or more properly a relvar) R to have an
> attribute A where A's type is the type of R am I declaring a fallacy
> or something that is logically possible (ignoring whether it has any
> use)?
>
> p
>

I do not know if the language of C.J. Date permits the definition of recursive type. One can define the type of a recursive relation in an invented language like this:

type R1 = Empty | Relation Integer x R1

Then instances of the type:

(1, (22, (10, (...(7, Empty)..))

It is not different from a list definition:

type List = Nil | Cons Integer x List

--
Tegi