El diagnóstico es la tarea de determinar si un sistema se comporta correctamente y, en caso contrario, identificar el componente fallido o el tipo de falla. En IA y razonamiento automatizado, los métodos diagnósticos usan observaciones del comportamiento del sistema para inferir causas probables de errores o malfuncionamientos.
Concerned with the development of algorithms and techniques that are able to determine whether the behaviour of a system is correct. If the system is not functioning correctly, the algorithm should be able to determine, as accurately as possible, which part of the system is failing, and which kind of fault it is facing. The computation is based on observations, which provide information on the current behaviour.