# What's tropical about tropical algebra?

Please allow me to ask a potentially dumb question (or maybe more precisely, a question floating on clouds of ignorance):

Why is a max-plus algebra called a tropical algebra?

• tropical refers to Brazil. Imre Simon working in Brazil was a pioneer of the field. – user2529 Sep 23 '11 at 8:30
• I see! But surely max-plus was studied even before Imre, or not? – Suvrit Sep 23 '11 at 8:33
• He was working at Sa\~o Paulo, I believe, and I think that this city is a little bit below the Capricorn tropic!! – Fernando Muro Sep 23 '11 at 8:39
• Warning: some Japanese authors use "tropicalization" to refer to lifting a max-plus formula to a rational function, which is what most Western authors call "detropicalization". I think the Japanese point of view makes better sense, in that a max-plus formula is like a zero Kelvin version, like Kashiwara's crystal basis. But it seems unlikely to be uprooted now. – Allen Knutson Sep 24 '11 at 1:46

• Given the name of the guy, why is it not called Balaton Geometry''? – Igor Rivin Sep 23 '11 at 8:37