Let \(m,n\) be positive integers and view \(S^1\) as the unit circle in the complex plane. Let \(X\) be the space obtained from the cylinder \(S^1\times [0,1]\) by identifying points \((z,0)\) and \((w,0)\) if \(z^n=w^n\), and identifying points \((z,1)\) and \((w,1)\) if \(z^m=w^m\).
- Use the Mayer-Vietoris sequence to compute \(H_i(X)\) for all \(i\).
- Use the Seifert-van Kampen theorem to find a presentation for \(\pi _1(X)\).