Two loops a
in a torus
A loop in mathematics, in a topological space X is a continuous function f from the unit interval I = [0,1] to X such that f(0) = f(1). In other words, it is a path whose initial point is equal to the terminal point.
A loop may also be seen as a continuous map f from the pointed unit circle S1 into X, because S1 may be regarded as a quotient of I under the identification of 0 with 1.
The set of all loops in X forms a space called the loop space of X.
- 1 2 Adams, John Frank (1978), Infinite Loop Spaces, Annals of mathematics studies, 90, Princeton University Press, p. 3, ISBN 9780691082066.