* Problem about relation of logical involution to to function space <math>Y^X = \{ f : X \to Y \}.</math>
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** Notice that a function <math>f : X \to Y</math> is a "<math>Y\!</math>-evaluator of every <math>X,\!</math> or a "giver of value in <math>Y\!</math> to everything in <math>X\!</math>".