This disclosure relates to a computer analysing log data. The computer receives log data comprising traces having log events from respective process executions. The computer creates a stream of log events, wherein the stream is sorted by the event time. The computer iterates over the stream of log events, and for each log event, executes update functions that define updates of a set of variables based on the log events. The set of variables comprises at least one cross-trace variable to calculate an updated value of the set of variables. The update functions define updates of the cross-trace variable in response to the log events of the traces. The computer further executes evaluation functions on the set of variables to determine complianc...