\myheading{CNF form}

\ac{CNF}\footnote{\url{https://en.wikipedia.org/wiki/Conjunctive_normal_form}} is a \emph{normal form}.

% TODO recheck
% TODO write abt it!
%\emph{normal form} is somewhat similar to polynomials in algebra. 
%What is polynomial?
%It is a standard way to express unsystematic equations like $2x \cdot x$ as $3x$ polynomial, 
%and so you will be able to apply some operations to polynomials like summing, etc.

Any Boolean expression can be converted to \emph{normal form} and \ac{CNF} is one of them.
The \ac{CNF} expression is a bunch of clauses (sub-expressions) consisting of terms (variables), ORs and NOTs, 
all of which are then glued together with AND into a full expression.
There is a way to memorize it: \ac{CNF} is ``AND of ORs'' (or ``product of sums'') and \ac{DNF} is ``OR of ANDs'' (or ``sum of products'').

Example is: $(\neg A \vee B) \wedge (C \vee \neg D)$.

$\vee$ stands for OR (logical disjunction\footnote{\url{https://en.wikipedia.org/wiki/Logical_disjunction}}), 
``+'' sign is also sometimes used for OR.

$\wedge$ stands for AND (logical conjunction\footnote{\url{https://en.wikipedia.org/wiki/Logical_conjunction}}).
It is easy to memorize: $\wedge$ looks like ``A'' letter.
``$\cdot$'' is also sometimes used for AND.

$\neg$ is negation (NOT).

% TODO A/B is the first clause, C/D is second
