This letter denotes ordinal numbers that are the fixed point of the exponential map. The Galois group of a field extension is linked to the properties of elliptic curves in a conjecture denoted by this letter that was proved by Ken Ribet. Transitions denoted by this letter can be used to simplify the state diagram of a nondeterministic finite automaton. For any positive number denoted by this letter, there exists a positive (*) delta that a function (10[1])is arbitrarily closed (10[1])to L in a definition of the limit. The identity element of the concatenation operation is denoted by this letter. A quantity denoted that characterizes the shapes of conic sections is called eccentricity. For 10 points, identify (10[1])this Greek letter that denotes the empty strings, which can also denote an arbitrarily small number. ■END■