covariation and declarative randomness RE: Re (2): Turing completeness and syntactic elegance;

On Monday, December 03, 2012 9:43 PM

Steve Schafer responds to Peter E.:

SS>>> ... complex relationships

SS>>> that are expressed declaratively rather than imperatively, ...

>> 

PE>>An example or two would be interesting.

 

SS>1) Perhaps the most commonly encountered example is SQL, especially the
WHERE clause. A >WHERE clause declaratively describes the relationship
between sets of columns.

 

This reminds me something that Eric Elder and I have struggled with quite a
bit in our proposal to add declarative randomness to SVG [1,2]. 

 

As our proposal and examples demonstrate is not too difficult to satisfy the
primary use cases for declarative randomness so that a) rich scenes may be
created and controlled with a minimum of code and effort by the author, and
b) the random seeds may be controlled so that scenes remain constant from
invocation to invocation. What we'd like to be able to add in, and welcome
suggestions for how to do it, is to be able to control the amount of
covariation between two random variables --- for example as the y position
of trees varies we might also want their brightness to increase (but with a
fixed coefficient of correlation). It is the co-dependency of random
variables for which we are trying to craft a declarative solution.

 

Cheers

David

 

 

 

[1] http://cs.sru.edu/~ddailey/svg/RandomTalk.html

[2] http://cs.sru.edu/~ddailey/serendipity.doc