Your cheap flights to Puerto Vallarta take you to a city dedicated to giving you a fun, relaxing vacation. The biggest attraction is the beach. But when you wish to do something more, you have endless options. Many spas, like Healing Hands, pamper and care for you. Davannayoga allows you to stretch and stay fit.
Definition. A metric space is a set X together with a function d (called a metric or distance function) which assigns a real number d (x, y) to every pair x, y X satisfying the properties (or axioms): 1  d (x, y) 0 and d (x, y) = 0 x = y, 2  d (x, y) = d (y, x), 3  d (x, y) + d (y, z) d (x, z).
#7. Any space with a null metric line running through it. It may be faster to go to the null line -- travel up the null line (which by definition takes no distance) -- and then travel to the second point than to take the straight line between points. For example, imagine a space with a null metric line running along the x=y, 45 degree line.