Neal Rubin, while driving his car in Chicago, inadvertently blocked the path of a Yellow Cab Co. taxi driven by Robert Ball, causing the taxi to swerve and hit Rubin’s car. Angered by Rubin’s driving, Ball got out of his cab and hit Rubin on the head and shoulders with a metal pipe. Rubin sued Yellow Cab Co. for the damages caused by this beating, contending that the employer was vicariously liable for the beating under the doctrine of respondent superior because the beating occurred in furtherance of the employer’s business, which was to obtain fares without delay. The company argued that Ball’s beating of Rubin was not an act undertaken to further the employer’s business. Is the employer liable under the theory of respondent superior?