text: For a group of sets of this type in the plane, if any three of the sets intersect, then they all intersect byHelly's Theorem.
full_question: For a group of sets of this type in the plane, if any three of the sets intersect, then they all intersect byHelly's Theorem. Two disjoint open sets of this type can always be separated by a hyperplane. Jensen'sinequality applies to functions described by this adjective, and basically states that a function's averagevalue across inputs is greater than that function of the average of the inputs. The smallest set of this typethat encloses a given set is known as that set's (*) "hull" of this type. A shape has this property if all linesegments between points in it remain in the figure. A function is described by this word if its second derivative ispositive. For 10 points, give this word that denotes polygons whose internal angles are all less than 180 degrees.
first_sentence: For a group of sets of this type in the plane, if any three of the sets intersect, then they all intersect byHelly's Theorem.
raw_answer:  convexity [accept any word forms]