# Multiplication is discontinuous in the Hawaiian earring group (with the   quotient topology)

**Authors:** Paul Fabel

arXiv: 0909.3086 · 2009-12-02

## TL;DR

This paper demonstrates that the multiplication operation in the fundamental group of the Hawaiian earring, equipped with the quotient topology, is discontinuous, providing a counterexample to a common assumption in topological group theory.

## Contribution

It introduces a specific example where the fundamental group with the quotient topology is not a topological group, answering a longstanding open question negatively.

## Key findings

- The quotient map q is not a quotient map when considering the product topology.
- The fundamental group of the Hawaiian earring is not a topological group under the quotient topology.
- The result settles the question of whether all such fundamental groups are topological groups, providing a negative answer.

## Abstract

The natural quotient map q from the space of based loops in the Hawaiian earring onto the fundamental group provides a new example of a quotient map such that q x q fails to be a quotient map.   This also settles in the negative the question of whether the fundamental group (with the quotient topology) of a compact metric space is always a topological group with the standard operations.

## Full text

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## References

10 references — full list in the complete paper: https://tomesphere.com/paper/0909.3086/full.md

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Source: https://tomesphere.com/paper/0909.3086