  Adversarial attacks against neural networks are a problem of considerable
importance, for which effective defenses are not yet readily available. We make
progress toward this problem by showing that non-negative weight constraints
can be used to improve resistance in specific scenarios. In particular, we show
that they can provide an effective defense for binary classification problems
with asymmetric cost, such as malware or spam detection. We also show the
potential for non-negativity to be helpful to non-binary problems by applying
it to image classification.
