Hello, Bonjour, Salut

Hi everybody, thank you for visiting !

There are four fundamental rules for a Wikipedian:

1) I am not necessary
2) The article is not necessary
3) Wikipedia is not necessary
4) Keep hydrated !

Oh! I am still a fan of Combinatorial species

BTW, what happened in the book ?

When defining the multi-sort on multi-sets, i.e. disjoint unions instead of unions, it was a huge loss.

PIE was lost, and multi-labelling was lost.

Items like aces of spades, that are both aces and spades, were outed and they missed the party.

to remove inline citation request

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by AMS and MIT footnotes are not welcomed in a mathematics article.