Q. about {0,1}-matrices.

[Artur]

Bug in title A125587	Call an nonsingular n X n matrix robust if the top  
left i X i submatrix is nonsingular for all i = 1..n.
Between an and n x n is necessary is add word nonsingular or invertible  
because without these word sequence will be different but possible to  
count without run computer programme

ARTUR


Dnia 08-01-2007 o 19:34:12 Artur <grafix at csl.pl> napisał(a):

> Dear Jonathan, Neil and Rest of Seqfans,
> In giving these names we have to think yet about next sequence 0 or 1,  
> 2, 40, 584,
> I don't have yet a(5).
> My proposal for these sequence follow Jonatan will be (because these is  
> gracile in comparision with these robust):
> Call an n X n matrix gracile if the top left i X i submatrix is  
> noninvertible for all i = 1..n.
> ARTUR
>
>
> Dnia 08-01-2007 o 18:34:21 Jonathan Post <jvospost3 at gmail.com>  
> napisał(a):
>
>> I suggest a better name for "binary matrices which are not robust":  
>> gracile.
>>
>> A126603 versus A125507.
>>
>> Robust and Gracile are antonyms, used as relative terms in  
>> paleoanthroplogy,
>> generally of bone proportions (i.e., thickness relative to length).
>> Frequently used for Australopithecus, as in "Australopithecus afarensis  
>> and
>> Australopithecus are known as gracile australopithecines, because of  
>> their
>> relatively lighter build, especially in the skull and teeth.  
>> Paranthropus
>> aethiopicus, robustus, and boisei are robust australopithecines."
>
>
>
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