"A Partial Differential Equation with a Subjective Variable"

A partial differential equation (PDE) describes how a quantity varies across multiple dimensions, like space and time. When a PDE involves a "subjective variable," it means one of the variables in the equation depends on personal or context-specific factors—such as individual preferences, perceptions, or decisions—that are not strictly determined by physical laws. This makes the equation not only a mathematical model of physical phenomena but also incorporates elements of human judgment or choice, adding a layer of complexity. Such equations are useful in fields like economics, psychology, or social sciences, where human factors influence the modeled processes.