# unlesss

## English

### Etymology

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

### Abbreviation

unlesss

1. (mathematics, logic) Precisely unless.
• 1990, James Glimm, The Legacy of John Von Neumann, American Mathematical Society, ISBN 0821814877, page 279,
Partial Order: GH unlesss (unless and only unless) H ≥ some GR or some HLG.
• 1999, V. K. Balachandran, Topological Algebras, 2000 North-Holland edition, ISBN 0444506098, pages 78–79 [1]:
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,
GH     unlesss HGR or HLG for some GRGR or some HLHL. ¶ (Analogous to “iff”, the term “unlesss” means “unless and only unless”.)