As the title states, what is the difference between \lnot and \neg? The output seems the same to me but I want to know if they are the exact same thing, both semantically and as code definition.

\(\lnot a \, \neg a\)


  • 2
    Similarly \land and \wedge represent the same symbol as do \lor and \vee.
    – egreg
    May 8, 2018 at 21:54

1 Answer 1


For your disappointment, none. They are the same.

If you run

\(\show\lnot a \, \show\neg a\)

you'll get:

> \lnot=\mathchar"23A.
l.3 \(\show\lnot
                 a \, \show\neg a\)
> \neg=\mathchar"23A.
l.3 \(\show\lnot a \, \show\neg

which shows that both are \mathchar"23A.

In fact, in plain.tex one finds:

\mathchardef\neg="023A \let\lnot=\neg

The same appears for other symbols as well:

\mathchardef\wedge="225E \let\land=\wedge
\mathchardef\vee="225F \let\lor=\vee
\def\neq{\not=} \let\ne=\neq
\mathchardef\leq="3214 \let\le=\leq
\mathchardef\geq="3215 \let\ge=\geq
\mathchardef\ni="3233 \let\owns=\ni
\mathchardef\leftarrow="3220 \let\gets=\leftarrow
\mathchardef\rightarrow="3221 \let\to=\rightarrow

My guess for the reason of this is that in different fields of applications these symbols get different names, so they have different names to make their utilization more intuitive.

In LaTeX, what happens is basically the same, but with a few more bells and whistles:


This can be found in fontmath.ltx (loaded by latex.ltx).

  • 1
    I imagine that also semantically I could consider them the same, right?
    – gvgramazio
    May 8, 2018 at 18:46
  • 3
    Yes, both are defined to be the same character. It's just two names for the same thing. May 8, 2018 at 18:55
  • 2
    There is another redefinition of them in unicode-math, as the Unicode character U+00AC. It also defines \lnot as an alias for \neg.
    – Davislor
    May 8, 2018 at 20:43
  • IIRC, ruby also has some under-the-hood-identical methods with different designations to, as @PhelypeOleinik said, "...make their utilization more intuitive."; that said, their documentation is usually nice enough to mention this. May 8, 2018 at 23:51

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