This guy I remember from gymnasium, I like those who challenge axioms and for the bolded text ;)

Nikolai Lobachevsky, Russian mathematician

Lobachevsky's main achievement is the development (independently from János Bolyai) of a non-Euclidean geometry, also referred to as Lobachevskian geometry. Before him, mathematicians were trying to deduce Euclid's fifth postulate from other axioms. Euclid's fifth is a rule in Euclidean geometry which states (in John Playfair's reformulation) that for

**any given line and point not on the line, there is one parallel line through the point not intersecting the line. Lobachevsky would instead develop a geometry in which the fifth postulate was not true.**[/b]

Non-Euclidean geometry is now in common use in many areas of mathematics and physics, such as general relativity; and hyperbolic geometry is now often referred to as "Lobachevskian geometry" or "Bolyai-Lobachevskian geometry".

A small part of him was Croatian, Natasa. Very small but there we go...

Sorry Seanus which small part would that be? I am quite convinced knowing his fathers and mothers family background.

I don't have anything against him being partially Croat, but the only Croatian thing about him was his place of birth. And even that was serbian populated area, not anymore.

But please, if you know something say, I would like to correct my wrong belief.