[seqfan] Re: No loop in view?

[Éric Angelini]

Many thanks Brad -- quite convincing !

à+
É.
Catapulté de mon aPhone


> Le 22 févr. 2019 à 23:16, Brad Klee <bradklee at gmail.com> a écrit :
> 
> Hi Eric,
> 
> Define {A,B} two edge-overlap tiles along one dimension, with an
> integer shift,
> 
> A=101,     B =11,      AB=1011,        BA=1101.
> 
> If you chop the first four terms and transform to {A,B} notation,
> 
> 11010111....
> BAABB...
> 
> then the letter sequence is the first column of a Post tag system:
> 
> Delete:1, Axiom: BA, Rule: A->BBA, B->A
> ===================================
> BA
> AA
> ABBA
> BBABBA
> BABBAA...
> 
> A slightly simplified example is:
> 
> Delete:1, Axiom: A, Rule: A->BA, B->A
> ===================================
> A
> BA
> AA
> ABA
> BABA
> ABAA
> BAABA...
> 
> With first column A003849.
> 
> I have not studied tag systems in detail, but will guess that the
> condition for periodic output is probably much more strict than
> for aperiodic output. Analogy with Fibonacci strongly suggests
> no looping for your sequence.
> 
> Cheers,
> 
> Brad
> 
> See also: http://mathworld.wolfram.com/TagSystem.html
> 
> 
>> On Fri, Feb 22, 2019 at 1:58 PM Éric Angelini <bk263401 at skynet.be> wrote:
>> Does someone have an idea about the sequence entering at some point
>> in a loop -- or never?