Symbols:Symbolic Logic/NAND

Logical NAND

 * $\uparrow$

Logical Nand.

A binary operation on two propositions.

$P \uparrow Q$ means not both $P$ and $Q$ together.

Also known as
The uparrow symbol $\uparrow$, when used in this context, is sometimes referred to as the Sheffer stroke, after.

However, that name properly belongs to the $\mid$ symbol.