Topological graph theory is a branch of mathematics that studies the interplay between graph theory and topology. It focuses primarily on the properties of graphs that are invariant under continuous transformations, such as stretching or bending, but not tearing or gluing. The key aspects of topological graph theory include: 1. **Graph Embeddings**: Understanding how a graph can be drawn in various surfaces (like a plane, sphere, or torus) without edges crossing.

K-theory is a branch of mathematics that studies vector bundles and more generally, topological spaces and their associated algebraic invariants. It has applications in various fields, including algebraic geometry, operator theory, and mathematical physics. The core idea in K-theory involves the classification of vector bundles over a topological space. Specifically, there are two main types of K-theory: 1. **Topological K-theory**: This version studies topological spaces and their vector bundles.

Double torus knots and links are concepts from the field of knot theory, which is a branch of topology. In topology, knots are considered as embeddings of circles in three-dimensional space, and links are collections of such embeddings. ### Double Torus A double torus is a surface that is topologically equivalent to two tori (the plural of torus) connected together. It's often visualized as the shape of a "figure eight" or a surface with two "holes.

Cohomology theories are mathematical frameworks used in algebraic topology, geometry, and related fields to study topological spaces and their properties. They serve as tools for assigning algebraic invariants to topological spaces, allowing for deeper insights into their structure. Cohomology theories capture essential features such as connectivity, holes, and other topological characteristics. ### Key Concepts in Cohomology Theories 1.

Polyadic algebra is a branch of algebra that extends the concept of traditional algebraic structures, such as groups, rings, and fields, to include operations that involve multiple inputs or arities. In particular, it focuses on operations that can take more than two variables (unlike binary operations, which are the most commonly studied).

The Leibniz operator is a differential operator used in the context of calculus, particularly in the formulation of differentiating products of functions. It is named after the mathematician Gottfried Wilhelm Leibniz, who made significant contributions to the development of calculus.

Cylindric algebra is a mathematical structure that arises in the study of multi-dimensional logics and is particularly relevant in the fields of model theory and algebraic logic. It is an extension of Boolean algebras to accommodate more complex relationships involving multiple dimensions or "cylindrical" structures. A cylindric algebra can be thought of as an algebraic structure that captures the properties of relations in multiple dimensions, enabling the representation of various logical operations and relations.

A **multiplicative character** is a type of mathematical function used in number theory, particularly in the context of Dirichlet characters and L-functions. Specifically, a multiplicative character is a homomorphism from the group of non-zero integers under multiplication to a finite abelian group, such as the group of complex numbers of modulus one.

A "two-graph" typically refers to a specific type of graph in the field of graph theory, but it might not be a widely standardized term. In general, graph theory involves studying structures made up of vertices (or nodes) connected by edges.

The Tutte matrix is a mathematical construct used in the study of graph theory, particularly in the context of understanding the properties of bipartite graphs and the presence of perfect matchings. It is named after the mathematician W. T. Tutte.

A Moufang set is a concept from the field of mathematics, specifically in the context of algebra and geometry. It is related to the study of certain types of algebraic structures that exhibit properties reminiscent of groups but without necessarily adhering to all the group axioms.

A symmetric graph is a type of graph that exhibits a certain level of symmetry in its structure. More formally, a graph \( G \) is considered symmetric if, for any two vertices \( u \) and \( v \) in \( G \), there is an automorphism of the graph that maps \( u \) to \( v \).