Task: Text Categorization
Input (English): The maximum possible volume for the geometric figure known as Gabriel's Horn is this quantity. The square root of two divided by two is the first product of an infinite sequence of terms named for Viete [vee-ET] that expresses this quantity. The value of the Riemann zeta function at two is equal to this quantity squared divided by six. The period of the tangent function is equal to this quantity. The number e raised to the product of i and this quantity is equal to negative one. For 10 points, name this transcendental number, the ratio of a circle's circumference to its diameter.
Output (English): Science