Fundamental system of a root system (source code)

= Fundamental system of a root system
{title2=$\Delta$}
{wiki=Root_system#Positive_roots_and_simple_roots}

A fundamental system $\Delta$ is a basis made of roots such that every root is a linear combination of $\Delta$ whose nonzero coefficients all have the same sign. Its members are the <simple root>[simple roots].

= Root basis
{synonym}