In topology, the wedge sum is a "one-point union" of a family of topological spaces. Specifically, if X and Y are pointed spaces (i.e. topological spaces with distinguished basepoints and ) the wedge sum of X and Y is the quotient space of the disjoint union of X and Y by the identification
where is the equivalence closure of the relation
More generally, suppose is a indexed family of pointed spaces with basepoints The wedge sum of the family is given by:
where is the equivalence closure of the relation
In other words, the wedge sum is the joining of several spaces at a single point. This definition is sensitive to the choice of the basepoints unless the spaces are homogeneous.
The wedge sum is again a pointed space, and the binary operation is associative and commutative (up to homeomorphism).
Sometimes the wedge sum is called the wedge product, but this is not the same concept as the exterior product, which is also often called the wedge product.
The wedge sum of two circles is homeomorphic to a figure-eight space. The wedge sum of circles is often called a bouquet of circles, while a wedge product of arbitrary spheres is often called a bouquet of spheres.
A common construction in homotopy is to identify all of the points along the equator of an -sphere . Doing so results in two copies of the sphere, joined at the point that was the equator:
Let be the map that is, of identifying the equator down to a single point. Then addition of two elements of the -dimensional homotopy group of a space at the distinguished point can be understood as the composition of and with :
Here, are maps which take a distinguished point to the point Note that the above uses the wedge sum of two functions, which is possible precisely because they agree at the point common to the wedge sum of the underlying spaces.
The wedge sum can be understood as the coproduct in the . Alternatively, the wedge sum can be seen as the of the diagram in the (where is any one-point space).
Van Kampen's theorem gives certain conditions (which are usually
This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.
In mathematics, a pointed space or based space is a topological space with a distinguished point, the basepoint. The distinguished point is just simply one particular point, picked out from the space, and given a name, such as that remains unchanged during subsequent discussion, and is kept track of during all operations. Maps of pointed spaces (based maps) are continuous maps preserving basepoints, i.e.
In mathematics, a rose (also known as a bouquet of n circles) is a topological space obtained by gluing together a collection of circles along a single point. The circles of the rose are called petals. Roses are important in algebraic topology, where they are closely related to free groups. A rose is a wedge sum of circles. That is, the rose is the quotient space C/S, where C is a disjoint union of circles and S a set consisting of one point from each circle. As a cell complex, a rose has a single vertex, and one edge for each circle.
In mathematics, specifically group theory, the free product is an operation that takes two groups G and H and constructs a new group G ∗ H. The result contains both G and H as subgroups, is generated by the elements of these subgroups, and is the “universal” group having these properties, in the sense that any two homomorphisms from G and H into a group K factor uniquely through a homomorphism from G ∗ H to K. Unless one of the groups G and H is trivial, the free product is always infinite.
Delves into disk deprivation in topology, showcasing how spaces emerge from this process.
In this thesis, we study two distinct problems.
The first problem consists of studying the linear system of partial differential equations which consists of taking a k-form, and applying the exterior derivative 'd' to it and add the wedge product with a 1- ...