Chebyshev system
= Chebyshev system
{c}
{title2=$\Phi=(u_0,\ldots,u_n)$}
= T-system
{c}
{synonym}
A Chebyshev system on a nondegenerate real interval is a family of $n+1$ real <continuous functions> such that every <linear combination> with coefficients not all zero has at most $n$ distinct zeros. The condition entails <linear independence> and unique interpolation at any $n+1$ distinct points. It is a zero-counting hypothesis, not a requirement to count multiplicities.