3. A system as in claim 1 , wherein each of the one or more symptoms comprises an error message with the corresponding symptom occurrence time comprising an error time extracted from the event reports from the user system.
1. A system for bug discovery using event reports, comprising: an interface configured to: receive symptom data extracted from event reports from a user system, wherein the symptom data is stored in a symptom database, and wherein the symptom data comprises one or more symptoms each with a corresponding symptom occurrence time; a processor configured to: determine an existence of one or more bugs of the user system based at least in part on a result of querying the symptom database using a bug definition, wherein the bug definition comprises a logic set operation on the symptom data, wherein the logic set operation comprises one of the following: AND, OR, XOR, MINUS, NOT, NAND, NOR or ADD.