Finding:

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   Poincaré conjecture

   The obvious generalization using simple-connectivity is false, but simply-connected, closed 3-manifolds are in fact the same class of spaces as homotopy 3-spheres.
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   Graph theory

   Enumerative graph theory then rose from the results of Cayley and the fundamental results published by Pólya between 1935 and 1937 and the generalization of these by De Bruijn in 1959. ... The introduction of probabilistic methods in graph theory, especially in the study of Erdős and Rényi of the asymptotic probability of graph connectivity, gave rise to yet another branch, known as random graph theory, which has been a fruitful source of graph-theoretic results.

Explore the following pages on Powerset:

• Poincaré conjecture,
• Graph theory