 According to the above definition, if "C" is a convex cone, then "C" ∪ {0} is a convex cone, too.A convex cone is said to be pointed if 0 is in "C", and blunt if 0 is not in "C".Blunt cones can be excluded from the definition of convex cone by substituting "non-negative" for "positive" in the condition of α, β.