Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Normally, when you have a long equation, you can split it on two lines. Suppose that $a$ and $b$ are very long expression. Then, for example:

$$ x = a - b$$

can be rewritten as

$$ x = a + $$ $$\quad-(b)$$

I use $+$ and $-$ to maintain a consistency. What do I have to do when using boolean operator? For example, I have to split into two lines the followings:

$$x = a \wedge b$$ $$x = a \vee b$$

Which is the correct way to do this?

share|cite|improve this question
up vote 1 down vote accepted

If you're trying to express conjunction $\land$ in terms of disjunction $\lor$, then you'll need to use the negation symbol $\lnot$ so you can use DeMorgan's: $$x = a\land b \iff x =\lnot(\lnot a \lor \lnot b)$$

Likewise, $$x = a \lor b \iff x = \lnot(\lnot a \land \lnot b)$$

If you're simply wanting to split lengthy propositions $a, b$ onto separate lines (for example when trying to format a paper which allows only at most a set number of characters per line, so that you cannot fit all of, say, $a \lor b$ on one line), then you can do either of the following: $$\begin{align} x &= (a) \lor \\ &\quad (b)\end{align}$$ or else $$\begin{align} x & = (a) \\&\quad \lor (b)\end{align}$$

Likewise for $x = a \land b$.

I put $a, b$ in parentheses to emphasize that the main connective is $\lor$, (or $\land$, repsectively): that we are connecting all of $a$ with all of $b$.

share|cite|improve this answer
the second part of your answer is what I was looking for! Thank you very much! – the_candyman Feb 22 '14 at 15:51
You're welcome. I added the second part because after rereading your question, it occurred to me that that might be what you were after! – amWhy Feb 22 '14 at 15:52

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.