unlesss

English

Etymology

Attributed to John Horton Conway. From unless, by analogy with the formation of iff from if.

Conjunction

unlesss

1. (mathematics, logic) Precisely unless.
   • 1990, James Glimm, The Legacy of John Von Neumann, American Mathematical Society, →ISBN, page 279,

     Partial Order: G ≥ H unlesss (unless and only unless) H ≥ some G^R or some H^L ≥ G.

   • 1999, V. K. Balachandran, Topological Algebras‎, North-Holland, published 2000, →ISBN, pages 78–79:

     A subset ${\displaystyle S}$ is called absorbing if to each ${\displaystyle x\in X}$ there is a real number ${\displaystyle \epsilon =\epsilon _{x}>0}$ such that ${\displaystyle \lambda x\in S}$ for all ${\displaystyle \lambda }$ with ${\displaystyle 0<\left|\lambda \right|\leq \epsilon }$. Trivially the set ${\displaystyle X}$ is absorbing; on the other hand ${\displaystyle \{0\}}$ can never be absorbing (unlesss ${\displaystyle X=\{0\}}$).

   • 2004, William Fraser, Susan Hirshberg, and David Wolfe, "The Structure of the Distributive Lattice of Games Born by Day n", in Integers: Electronic Journal of Combinatorial Number Theory 5(2) (2005), page 2,

     G ≥ H     unlesss H ≥ G^R or H^L ≥ G for some G^R ∈ G^R or some H^L ∈ H^L. ¶ (Analogous to “iff”, the term “unlesss” means “unless and only unless”.)

References

• MathWorld

Anagrams

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