De Gua's theorem is a result in geometry that relates to right tetrahedra. It states that in a right tetrahedron (a four-faced solid where one of the faces is a right triangle), the square of the area of the face opposite the right angle (the right triangle) is equal to the sum of the squares of the areas of the other three triangular faces.

In geometry, a half-space refers to one of the two regions into which a hyperplane (a flat subspace of one dimension less than the ambient space) divides the space.

"On Conoids and Spheroids" is a notable work by the mathematician Giovanni Battista Venturi that was published in 1719. The treatise addresses the geometric properties of conoids and spheroids, which are forms generated by rotating curves around an axis. **Conoids** are surfaces generated by rotating a conic section (like a parabola) around an axis. They can exhibit interesting properties, such as the ability to create areas of uniform density when shaped correctly.

The Theorem of the Gnomon is a mathematical concept related to geometric figures, particularly in the context of areas. Although it is not as commonly referenced as other theorems, it essentially deals with the relationship between certain geometric shapes, particularly in relation to squares and rectangles. The term "gnomon" refers to a shape that, when added to a particular figure, results in a new figure that is similar to the original.

Cellular homology is a tool in algebraic topology that allows for the computation of homology groups of a topological space by using a cellular structure derived from a CW-complex. A CW-complex is a kind of topological space that is built up from basic building blocks called cells, which are homeomorphic to open disks in Euclidean space, glued together in a specific way.

The Hodge conjecture is a fundamental statement in algebraic geometry and topology that relates the topology of a non-singular projective algebraic manifold to its algebraic cycles. Formulated by W.V. Hodge in the mid-20th century, the conjecture suggests that certain classes of cohomology groups of a projective algebraic variety have a specific geometric interpretation.

Poincaré duality is a fundamental theorem in algebraic topology that describes a duality relationship between certain topological spaces, particularly manifolds, and their cohomology groups. Named after the French mathematician Henri Poincaré, the theorem specifically applies to compact, oriented manifolds.

In homotopy theory, a branch of topology, theorems often deal with properties of spaces and maps (functions between spaces) that remain invariant under continuous deformations, such as stretching and bending, but not tearing or gluing.

The Cotangent complex is a fundamental construction in algebraic geometry and homotopy theory, especially within the context of derived algebraic geometry. It can be seen as a tool to study the deformation theory of schemes and their morphisms.

The Whitehead product is a concept from algebraic topology, specifically in the context of algebraic K-theory and homotopy theory. It is named after the mathematician G. W. Whitehead and plays a significant role in the study of higher homotopy groups and the structure of loop spaces. In general, the Whitehead product is a binary operation that can be defined on the homotopy groups of a space.

The Atiyah–Hirzebruch spectral sequence is an important tool in algebraic topology, specifically in the computation of homotopy groups and cohomology theories. It provides a way to calculate the homology or cohomology of a space using a spectral sequence that is associated with a specific filtration. The original context for the spectral sequence primarily relates to complex vector bundles and characteristic classes.

The Milnor conjecture, proposed by John Milnor in the 1950s, is a statement in the field of algebraic topology, particularly concerning the nature of the relationship between the topology of smooth manifolds and algebraic invariants known as characteristic classes. The conjecture specifically relates to the Milnor's "h-cobordism" theorem and the properties of the "stable" smooth structures on high-dimensional manifolds.

Knot theory is a branch of mathematics that studies knots, their properties, and the various ways they can be manipulated and classified. Here is a list of topics within knot theory: 1. **Basic Concepts** - Knots and links: Definitions and examples - Open and closed knots - Tangles - Reidemeister moves - Knot diagrams 2. **Knot Invariants** - Fundamental group - Knot polynomials (e.g.

The term "Ribbon category" could refer to different concepts depending on the context in which it is used. However, it is often associated with specific types of user interface design, data visualization, or organizational structures. Below are a few interpretations: 1. **User Interface Design**: In software applications, a "ribbon" refers to a graphical control element in the form of a set of toolbars placed on several tabs.

Esakia duality is a correspondence between two categories: the category of certain topological spaces (specifically, spatial modal algebras) and the category of certain algebraic structures known as frame homomorphisms. This duality is named after the mathematician Z. Esakia, who developed the theory in the context of modal logic and topological semantics.

A **convex cap** typically refers to a mathematical concept used in various fields, including optimization and probability theory. However, the term might also be context-specific, so I’ll describe its uses in different areas: 1. **Mathematics and Geometry**: In geometry, a convex cap can refer to the convex hull of a particular set of points, which is the smallest convex set that contains all those points.

Verdier duality is a concept from the field of algebraic geometry and consists of a duality theory for sheaves on a topological space, particularly in the context of schemes and general sheaf theory. It is named after Jean-Louis Verdier, who developed this theory in the context of derived categories. At its core, Verdier duality provides a way to define a duality between certain categories of sheaves.

In category theory, the concept of an **end** is a particular construction that arises when dealing with functors from one category to another. Specifically, an end is a way to "sum up" or "integrate" the values of a functor over a category, similar to how an integral works in calculus but in a categorical context.

Ind-completion is a concept from the field of category theory, specifically related to the completion of a category with respect to a certain type of structure or property. In mathematical contexts, "ind-completion" often refers to a way of completing a category by formally adding certain limits or colimits.

A string diagram is a visual representation used in various fields, most prominently in mathematics and physics, particularly in category theory and string theory. The term may be interpreted in different contexts, but here are the two primary uses: 1. **String Diagrams in Category Theory**: - In category theory, string diagrams are a way to visualize morphisms (arrows) and objects (points) within a category.