SchließernOperatoren
SchließernOperatoren, a term originating from German, translates roughly to "closing operators" or "lock operators." In the context of theoretical physics and mathematics, particularly in quantum mechanics and functional analysis, it refers to a specific type of mathematical operator. These operators are characterized by the property that their spectrum, which describes the possible outcomes of measurements, is "closed" in a particular sense. More formally, an operator $A$ is considered a SchließernOperator if its domain of definition, when extended appropriately, forms a closed set in the relevant function space. This closure property is crucial for ensuring the well-posedness of certain mathematical problems and the stability of physical systems.
The concept is often encountered when dealing with unbounded operators, which are common in quantum mechanics,