We present a randomized and a deterministic data structure for maintai
ning a dynamic family of sequences under equality tests of pairs of se
quences and creations of new sequences by joining or splitting existin
g sequences. Both data structures support equality tests in O(1) time.
The randomized version supports new sequence creations in O(log(2) n)
expected time where n is the length of the sequence created. The dete
rministic solution supports sequence creations in O(log n (log m log
m + log n)) time for the mth operation.