[Python-Dev] re: Using lists as sets

[Christian Tismer]

Jean-Claude Wippler wrote:
[relational notation]

>   A vector (sequence) is:  #:R1,R2,...,RM
>   A set is:                K1,K2,...KN:
>   A multi-set is:          K1,K2,...KN,#:
>   A map is:                K1,K2,...KN:#,R1,R2,...,RM
>   A multi-map is:          K1,K2,...KN,#:R1,R2,...,RM

This is a nice classification!
To my understanding, why not
   A map is:                K1,K2,...KN:R1,R2,...,RM

Where is a # in a map?

And what do you mean by N and M?
Is K1..KN one key, mae up of N sub keys, or do you mean the
whole set of keys, where each one is mapped somehow.
I guess not, the notation looks like I should think of tuples.
No, that would imply that N and M were fixed, but they are not.
But you say
"- collections consist of objects, each of them with attributes".
Ok, N and M seem to be individual for each object, right?

But when defining a map for instance, and we're talking of the
objects, then the map is the set of these objects, and I have to
think of
  K[0]..K(N(o)):R[0]..R(M(o))
where N and M are functions of the individual object o, right?

Isn't it then better to think different of these objects, saying
they can produce some key object and some value object of any
shape, and a position, where each of these can be missing?

ciao - chris

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