The $\varepsilon$-observability property for distributed-parameter systems

We analyse observability problem for distributed-parameter systems within the framework of “the guaranteed estimation theory”. Here the observability properties of system are defined through the characteristics of an informational domain that is consistent with the measurement data. The new property "$\varepsilon$-observability of system" at specified instant of time is detected. The obtained results are interpreted in terms of controllability problem for the dual system.