That's simply a matter of the definition!
The break point is the (minimum) value of
such that
no set of
points can be shattered. To put it another way, it is the (minimum) value of
such that
every set of
points fails to be shattered. Finding one set of
points that fails to be shattered is
consistent with the existence of a break point, but you need to demonstrate
all other sets of
points have the same property.
