  For arbitrary undirected graph $G$, we are designing SATISFIABILITY problem
(SAT) for HCP, using tools of Boolean algebra only. The obtained SAT be the
logic formulation of conditions for Hamiltonian cycle existence, and use $m$
Boolean variables, where $m$ is the number of graph edges. This Boolean
expression is true if and only if an initial graph is Hamiltonian. That is,
each satisfying assignment of the Boolean variables determines a Hamiltonian
cycle of $G$, and each Hamiltonian cycle of $G$ corresponds to a satisfying
assignment of the Boolean variables. In common case, the obtained Boolean
expression may has an exponential length (the number of Boolean literals).
