t-designs

[Peter Dobcsanyi]

I have added an indicator called <t_design> to the ext-rep schema:

    element t_design {
        attribute value { xsd:boolean } ,
        attribute maximum_t { xsd:positiveInteger } ?
    } ?

Proposed semantics: value is "true" when the design is equireplicate
with constant_blocksize and maximum_t is minimum 2.

We currently have:

    t_design_properties = element t_design_properties { 
	# temporary, will change
	element parameters {
	    attribute t      { xsd:positiveInteger } ,
	    attribute v      { xsd:positiveInteger } ,
	    attribute b      { xsd:positiveInteger } ,
	    attribute r      { xsd:positiveInteger } ,
	    attribute k      { xsd:positiveInteger } ,
	    attribute lambda { xsd:positiveInteger } ,
	    empty
	} , 
	indicators	# specific to t-designs
    }   

What should the value of t be here? One possibility is maximum_t.
Another is let it be driven by query, that is to have whatever the user
asked for in a query. I am suggesting the latter one, do not forget
ext-rep is going to be a query language too.

Without going too far (or even implementing them in the current Writers
right now) we need a few indicators which make sense only for t-designs.
For example <steiner_triple_system>. Could you, please, suggest a few
sensible ones. Then we could ask more during the public debate --
probably we are going to get more than we can accommodate even if we don't
ask for it :-)

By the way we still need a good name to replace "flag_entry" to settle
<t_wise_balanced> and <alpha_resolvable>. Any new ideas?

--             ,
    Peter Dobcsanyi