"Frank Rosenblatt... invented a very simple single-layer device called a Perceptron. ...Unfortunately, its influence was damped by Marvin Minsky and Seymour Papert, who proved [in Perceptrons: An Introduction to Computational Geometry (1969)] that the Perceptron architecture and learning rule could not execute the "exclusive OR" and therefore could not learn. This killed interest in Perceptrons for a number of years... It is possible to construct multilayer networks of simple units that could easily execute the exclusive OR... Minsky and Papert would have contributed more if they had produced a solution to this problem rather than beating the Perceptron to death."