= Nicolaas Govert de Bruijn
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<Nicolaas Govert de Bruijn> worked on <combinatorics> and mathematical structures. With <Paul Erdős>, he proved a finite incidence theorem in their 1948 paper: a nontrivial system in which each pair of points lies on exactly one line has at least as many lines as points.<On a combinatorial problem by Nicolaas Govert de Bruijn and Paul Erdős>[Original byline and Theorem 1]{ref}
The equality cases are highly organized: a near-pencil or a finite projective plane. This shows how a local pair-incidence rule controls both a global counting inequality and the structure of extremal examples.<On a combinatorial problem by Nicolaas Govert de Bruijn and Paul Erdős>[Theorem 1 and equality characterization]{ref}
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