in reply to Sets of subsets
You might find Set::Partition or the partitions method of Algorithm::Combinatorics helpful.
An Englishman in New York
An American Werewolf in London
An American in Paris
The Innocents Abroad
An Idiot Abroad
Robinson Crusoe on Mars
A Connecticut_Yankee in King Arthur's Court
There and Back Again
Travels into Several Remote Nations of the World
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