1. A method for unsupervised detection of an anomaly in the operation of a computer system comprising the steps of: (a) receiving a set of unlabeled data instances which do not indicate any anomaly occurrence, the set of unlabeled data instances corresponding to a computer operation and having features; (b) implicitly mapping the set of unlabeled data instances to a feature space; (c) calculating one or more sparse regions in the feature space; and (d) designating one or more data instances from the set of unlabeled data instances as an anomaly if said one or more data instances is located in said one or more sparse regions of the feature space.