We know that for each topological space (say path connected), $\pi_{1}(X)$ is a group, the fundamental group of $X$. But if we take a group $G$, exists there a topological space X such that $\pi_{1}(X)=G$ ?
2026-04-05 18:50:07.1775415007
Is the functor $\pi_{1}$ essentially surjective?
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