Zendo, play by forum

[Proxima]

Having buddha nature:
PLAY

Lacking buddha nature:
RE
ZENDO
ELEUSIS
BY
FORUM

[Nepster]

AC
CA
NTOR
TORN
FMAT

[Proxima]

Having buddha nature:
NTOR
TORN
FMAT

Lacking buddha nature:
AC
CA

[Clam]

EU
CLID
LER
HAVING
LACKING

[Proxima]

Having buddha nature:
LER
CLID
HAVING (appropriately)

Lacking buddha nature:
EU
LACKING 

[Nepster]

L
CID
TOR
TON
TRN
ORN

[Proxima]

Having buddha nature:
CID
TOR
TON
TRN
ORN

Lacking buddha nature:
L

[Clam]

LEMMINGSFORUMS
PLAYBYFORUM
HAVINGLACKING
BUDDHANATURE

[Proxima]

^ All black.

[Clam]

Then I guess that AKHTBN iff its length is 3, 4, 6, 9 or 10.

[Proxima]

That is not correct. For example, BERTRANDRUSSELL does have buddha nature.

Added from chat:

Having buddha nature:
RHABARBAHARABAHARBARA
MAURITSCORNELISESCHER
ABCDEFGHIJKLMNOP
HONORIFICABILITUDINITATIS

Lacking buddha nature:
ABCDEFGH
AABBAABI
CCBBCCBI
MAAABBBI
DOUGLASHOFSTADTER
DOUGLASRHOFSTADTER
SIMONNXXXXXXX
Y
ABCDEFGHIJKLMNOPQ
HONORIFICABILITUDINITATIBUS
RHUBARB
LADISLAUSBORTKIEWICZ

[Proxima]

Clam guessed the correct rule in chat. The length must be a square or triangular number, but not both.

[Clam]

I even proposed a koan of length 36 just to be sure

---

New round:

ALABAMA has the buddha nature
and
MISSISSIPPI does not have the buddha nature.

[Ramon]

AKHTBN iff there's only one unique letter of the alphabet having the most occurances in the koan.

[Simon]

AKHTBN iff exactly one letter appears more than once in the koan.
AKHTBN iff at most one letter appears more than once in the koan.

PORCUPINE
KOANPINE
PINECONE
CONECONE
INVISIBLE
I

-- Simon