On the Complexity of the Class of Regions Computable by a Two-Layered Perceptron Eddy Mayoraz Abstract: This work is concerned with the computational complexity of the recognition of $\LPtwo$, the class of regions of the Euclidian space that can be classified exactly by a two-layered perceptron. Several subclasses of $\LPtwo$ of particular interest are also considered. We show that the recognition problems of $\LPtwo$ and of other classes considered here are intractable, even in some favorable circumstances. We then identify special cases having polynomial time algorithms.