User:Harryboyles/Epsilon

• Hilbert introduced epsilon terms $|\epsilon x.\phi$ as an extension to first-order logic; see epsilon calculus.
• it is used to represent the Levi-Civita symbol.
• it is used to represent dual numbers: $a+b\varepsilon$, with $|\varepsilon ^{2}=0$ and $|\varepsilon \neq 0$.