Consider the group \(G\) given by the presentation
\[ G=\langle a,b\mid a^p b^q=1\rangle \]
where \(p\), \(q\) are given integers.
- Construct a (connected) CW-complex \(X\) with a basepoint \(x\) such that \(\pi _1(X,x)\cong G\).
- Compute \(H_1(X)\) and give conditions on \(p\), \(q\) that are equivalent to \(H_1(X)\) being torsion-free.