Complex sentence: However, the goal of Milner and Hoare to attain an algebraic calculus led to a critical divergence from the Actor model: communication in the process calculi was not direct as in the Actor model but rather indirectly through channels (see Actor model and process calculi).
Split into simpler sentences: However, the goal of Milner and Hoare to attain an algebraic calculus led to a critical divergence from the Actor model. Communication in the process calculi was not direct as in the Actor model but rather indirectly through channels (see Actor model and process calculi).