Просмотр кода страницы Nowhere-zero k-flow

'''Nowhere-zero <math>k</math>-flow''' --- нигде не нулевой <math>k</math>-поток, везде ненулевой <math>k</math>-поток. 

A graph admits a ''' nowhere-zero <math>k</math>-flow''' (<math>k</math> is an integer <math>\geq 2</math>) if
its edges can be oriented and labeled by numbers from <math>\{\pm1, \ldots,
\pm(k-1)\}</math> so that for every vertex the sum of the incoming values
equals the sum of the outcoming ones. A graph without ''' nowhere-zero <math>k</math>-flow'''
is called ''' <math>k</math>-snark'''. Note that if a graph is a <math>k</math>-snarks then
it is a <math>k'</math>-snark for any integer <math>2 \leq k' \leq k</math>. Very famous is
the ''' 5-flow conjecture''' of W.T.Tutte which says that there are no
bridgeless 5-snarks.