Symbols / greek letters are used in mathematical notation for variables, functions etc. and commonly informs the reader that it is definied within a conventional accepted range. What is the most common symbol for a bit / two-state integer?

I found maybe the $\xi$ symbol can be used? or maybe something else is used.

For example $\xi\in\mathbb{Z^+}$ where $\xi$ can either be $0$ or $1$. $\xi \equiv 0 |1\pmod 2$

Question is; which symbol is commonly used for a two state variable?

  • 2
    $\begingroup$ So long as you define it, it doesn't really matter what symbol you use. That being said, $\chi$ appears in several contexts as indicator variables / indicator functions / random variables such as here and would have been my first choice outside of using $a,\alpha,x$. $\endgroup$
    – JMoravitz
    Commented Nov 14, 2018 at 23:16
  • $\begingroup$ @JMoravitz Ok. I like $\alpha$. I might just use that. And yeah, I could have added that the variable I need a greek letter for acts like a flag (on or off) etc. $\endgroup$
    – user366820
    Commented Nov 14, 2018 at 23:23

1 Answer 1


It is very common to use the letter y for binary variables. y1, y2, y3 etc.

I don't think there is any Greek letter particularly used for this.


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