#Symetric Chain Decomposition:

SDC:=proc(n):

if n=0 then
RETURN ({[{}]}):
fi:


CD:={}:

X:=SDC(n-1):
for i from 1 to nops(X) do
k:=nops(X[i]):
CD:=CD union {[op(X[i]),op(k,X[i]) union {n}]}:
if k<>1 then
CD:=CD union {[seq(op(j,X[i]) union {n},j=1..k-1)]} :
fi:
od:

CD:

end: