Complex sentence: He taught at the Universität Heidelberg as well as in US universities; at Chicago, he was a guest of his friend Schumpeter, with whom he shared the interest in the theory of the economic cycle.
Split into simpler sentences: He taught at the Universität Heidelberg as well as in US universities. At Chicago, he was a guest of his friend Schumpeter, with whom he shared the interest in the theory of the economic cycle.