P.M.Akhmetiev

On a higher analog of the linking number of two curves

In the paper two invariants of strangeness type are constructed for
Prem-ornaments, i.e., for curves that are the projections on the
plane of knots or two-component links lying in 3-space. These
invariants are used to generalize M.~Friedman's theorem: it is proved
that there exists a lower bound for the energy of a magnetic field
frozen into a conducting liquid medium.