[seqfan] Re: Decimal concatenation of permutations

Richard Mathar mathar at strw.leidenuniv.nl
Fri Apr 30 16:16:15 CEST 2010

http://list.seqfan.eu/pipermail/seqfan/2010-April/004520.html says

cg> Date: Thu, 29 Apr 2010 09:35:15 -0400
cg> To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
cg> Subject: [seqfan]  Decimal concatenation of permutations
cg> ...
cg> The examples include one partitions listed in nonincreasing order
cg> (3,1) and one in nondecreasing order (1,1,2).  I get different
cg> sequences depending on what orderings I allow:
cg> 1,2,111,112,5,11112	nondecreasing only
cg> 1,2,111,4,5,222	nonincreasing only
cg> 1,2,111,112,5,11112	all orderings allowed

The generic rule is: "If the definition does not specify
constraints, these constraints do not exist." In this case here,
all orderings are allowed, and this selects one natural
correction to the original entries.

(My habit is to add these variants in comments to save time to
any reader asking the very same question. In the rare circumstances which
place these variants into the class of "interesting" sequences--certainly
not in the base dependent cases or those that are confusing because they
allow a range of different interpretations--I'd submit new sequences to
cover these too.)


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