The boundary of a convex set is always a convex curve. The intersection of all convex sets containing a given subset A of Euclidean space is called the convex hull of A. It is the smallest convex set containing A.
Rector (ecclesiastical) A rector is, in an ecclesiastical sense, a cleric who functions as an administrative leader in some Christian denominations, and in Islam. In contrast, a vicar is also a cleric but functions as an assistant and representative of an administrative leader.
This distinction was enforced by the development of canon law, by which the construction and upkeep of the chancel was the responsibility of the rector, whereas the construction and upkeep of the nave was the responsibility of the parish.