|Zero: is a natural number that is used to express that no object meets a certain condition or that a measured value has this quantity with respect to a unit of measure.|
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|Berka I 121
Definition Zero/O/Number/Logical Form/Hilbert:
0(F) : ~(Ex)F(x)
"There is no x for which F applies."
K. Berka/L. Kreiser
Logik Texte Berlin 1983