New subject: [math-fun] Is there a name for permutations that preserve no consecutive pairs?

18 Aug 2017


      Maybe the Daily Mail used "peninsulas" as a verb, but not to worry:
No newspaper would ever do that.

—Dan
...
From: Bill Gosper <billgosper@gmail.com>
...
On 2017-08-18 13:21, Dan Asimov wrote:
...
Don't know a name for this, other than "well-mixed anagrams".
megachiropteran
cinematographer
—Dan
Or not.
In[105]:= unshuf["megachiropteran", "cinematographer"]
Out[105]= {"ra"}  --rwg
Gack.  The Daily Mail just used peninsulas as a verb.
...
Bill Gosper wrote:
-----
I find them surprisingly tricky to eyeball correctly.
Although I caught this one.  --rwg
...
E.g.,
unshuf[a_String, b_String] :=
 StringCases[a ~~ "¢" ~~ b, ___ ~~ x_ ~~ y_ ~~ ___ ~~ "¢" ~~ ___ ~~ x_ ~~
y_ ~~ ___ :> x ~~ y]
TableForm[{#, unshuf @@ #} & /@ {{"aniseed oils",
    "loin disease"}, {"disanimate", "mediastina"}, {"pericleans",
"linespacer"}, {"scalyanteaters",
    "transacetylase"}, {"laborintensive", "inventoriables"},
{"pleonastic",
"pointlaces"}, {"celeritous",
    "reticulose"}, {"linesofcredit", "selfdirection"}, {"nitrosamines",
    "nestorianism"}, {"crucible steel", "electric blues"}, {"blueshirt",
"thuribles"}, {"cornmeals",
    "macrolens"}, {"cathartine", "anthracite"}, {"treelawns",
"waterlens"}, {"dipstream", "predatism"}},
 TableSpacing -> {1, 49}]
aniseed oils
loin disease                                                   oi
disanimate
mediastina                                                     di
pericleans
linespacer                                                     er
scalyanteaters
transacetylase                                                 an
laborintensive
inventoriables                                                 ve
pleonastic
pointlaces
celeritous
reticulose
linesofcredit
selfdirection                                                  di
nitrosamines
nestorianism                                                   es
crucible steel
electric blues                                                 el
blueshirt
thuribles                                                      es
cornmeals
macrolens
cathartine
anthracite                                                     th
treelawns
waterlens                                                      ns
dipstream
predatism                                                      re
redtapism
spermatid
ammonolytic
commonality                                                 on
partleading
plantigrade                                                 ad
astonished
dositheans                                                  he
alicesfern
craneflies                                                  es
discrepate
pederastic
forcertain
refraction
camelspider
premedicals                                                 ls
bestarred
redbreast                                                   ed
apostlebird
pilotsbread
-----

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Re: [math-fun] Is there a name for permutations that preserve no consecutive pairs?

Dan Asimov

Fred Lunnon

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