The symbol of the Hellenic Semester 2014 in Ispra is located at the main roundabout inside the JRC campus and it consists of the 3 Greek letters π δ φ. They do not stand for "pdf" as someone had thought, but they were selected by the Greek organising committee as those which the best illustrate the connection between the Greek Alphabet and science.

pi The pi [π] represents the universally known mathematical constant that is the ratio of a circle’s circumference to its diameter and is approximately equal to 3.14159. The Greek letter was adopted based on the Greek word περίμετρος - perimeter.
delta The delta [δ] in mathematics is also used as the Kronecker delta, which, in a simplified way, corresponds to the diagonal (διαγώνιος) of a matrix. It is also the first letter of the Greek word δημοκρατία - democracy. This word was coined from δῆμος (dêmos) ‘‘people’’ and κράτος (kratos) ‘‘power’’ or ‘‘rule’’ in the 5th century B.C. to represent the ‘‘rule of the people’’ political systems, present at the time in Greek city-states, notably Athens
phi The phi [φ] in mathematics, art and architecture represents the golden ratio also known as divine proportion, which is approximately equal to 1.61803. It is also the first letter of the Greek word φιλοσοφία - philosophy, extremely significant in Greek culture and the world since the 6th century B.C.

EU Presidency GR. Hellenic Semester opening ceremony at JRC Ispra. Group photo near the Semester symbol