\newpage\subsection{Complexity of NP Problems.\label{compl}}
We determined that inversion, search, and NP types of problems are equivalent.
Nobody knows whether {\em all} such problems are solvable in P-time
(i.e.\ belong to P). This question (called P=?NP) is probably the most famous
one in Theoretical Computer Science. All such problems are solvable in
exponential time but it is unknown whether any better algorithm generally
exists. For many problems the task of finding an efficient algorithm may seem
hopeless, while similar or slightly relaxed problems can be solved. Examples:
\begin{enumerate}
\item Linear Programming: Given integer $n\times m$ matrix $A$ and
vector $b$, find a rational vector $x$ with $Ax