There are several places in topology where the Chinese Remainder Theorem (CRT) can be seen. One example is in the study of covering spaces. The CRT states that if we have two relatively prime integers, then there exists a solution to a system of congruences. In topology, we often use covering spaces to study the fundamental group of a space. The fundamental group is a group that measures the number of "holes" in a space. In order to construct covering spaces, we often use the CRT to find solutions to certain systems of congruences.
Another place where the CRT can be seen in topology is in the study of knots. A knot is a closed loop in three-dimensional space that does not intersect itself. In knot theory, we often use the CRT to classify knots based on their symmetries. By applying the CRT, we can determine if two knots are equivalent or not.
Furthermore, the CRT can also be used in the study of manifolds. A manifold is a topological space that locally looks like Euclidean space. In particular, the CRT is used in the construction of torus bundles over manifolds. This is a type of fiber bundle that is topologically equivalent to a torus. The CRT is used to determine the structure of these bundles.
In summary, the Chinese Remainder Theorem has various applications in topology, such as in the study of covering spaces, knots, and manifolds. It provides a useful tool for solving systems of congruences and understanding the structure of certain topological spaces.