Area of a circle as follows. Draw a perpendicular from the center to the midpoint of a side of the polygon; its length, "h", is less than the circle radius. Also, let each side of the polygon have length "s"; then the sum of the sides, "ns", is less than the circle circumference. The polygon area consists of "n" equal triangles with height "h" and base "s", thus equals ⁄"nhs". But since "h" < "r" and "ns" < "c", the polygon area must be less than the triangle area, ⁄"cr", a contradiction. Therefore, our supposition that "C" might be greater than "T" must be
Straight-line grammar minimal size that generates a given string is called the smallest grammar problem. Straight-line grammars (more precisely: straight-line context-free string grammars) can be generalized to "Straight-line context-free tree grammars". The latter can be used conveniently to compress trees. A context-free grammar "G" is an SLG if: 1. for every non-terminal "N", there is at most one production rule that has "N" as its left-hand side, and 2. the directed graph "G"=<"V","E">, defined by "V" being the set of non-terminals and ("A","B") ∈ "E" whenever "B" appears at the right-hand side of a production rule for "A", is acyclic. A mathematical