ground

In mathematical logic, a ground term of a formal system is a term that does not contain any variables. Similarly, a ground formula is a formula that does not contain any variables.
In first-order logic with identity with constant symbols



a


{\displaystyle a}
and



b


{\displaystyle b}
, the sentence



Q
(
a
)
∨
P
(
b
)


{\displaystyle Q(a)\lor P(b)}
is a ground formula. A ground expression is a ground term or ground formula.

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