# Matthew Russell
# Experimental Math
# Homework 22
# I give permission to post this

read `public_html/em12/split.txt`:

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# Using split(w1,w2), that returns true if and only if w1w2 splits into w1.w2, write a procedure
# SplitUp(L),
# that inputs a list in {1,2,3}*, L,
# and outputs it as a list of lists
# [L1,L2,L3, ...]
# where L=[op(L1),op(L2), op(L3), ...]
# and L1,L2,L3, are atoms. 

SplitUp:=proc(L) local K,pos,i,j,k,flag:
option remember:

K:=[]:
pos:=1:
for i from 1 to nops(L) do
	flag:=true:
	for j from i to nops(L) while flag do
		for k from j+1 to nops(L) do
			if split([op(i..j,L)],[op(j+1..k,L)]) and SplitUp([op(j+1..nops(L),L)])[1]=[op(j+1..k,L)] then
				K:=[op(K),[op(i..j,L)]]:
				i:=j:
				pos:=j+1:
				flag:=false:
				break:
			fi:
		od:
	od:
od:

return [op(K),[op(pos..nops(L),L)]]:

end: