A variant form of the capital Pi symbol commonly used in category theory and mathematical logic.
Examples
Product notation in calculus
\varPi_{i=1}^n x_i = x_1 \cdot x_2 \cdot \ldots \cdot x_n
Profit function in economics
\varPi(q) = TR(q) - TC(q)
Projection operator in linear algebra
\varPi: V \rightarrow W \text{ where } \varPi^2 = \varPi