A tetradic number is a concept from number theory that refers to a specific type of number. A number \( n \) is considered a tetradic number if it can be expressed as the sum of two squares in two different ways.

The Toy Theorem is a concept from mathematical logic, specifically in the context of set theory and model theory. However, it isn't widely recognized as a fundamental theorem like Gödel's Incompleteness Theorems or the Zermelo-Fraenkel axioms of set theory.

The Uniqueness Theorem is an important concept in various fields of mathematics, particularly in calculus, complex analysis, and differential equations. The specific details can vary depending on the context in which it is applied.

Univariate analysis refers to the examination of a single variable in a dataset. The term "univariate" comes from "uni," meaning one, and "variate," which refers to a variable. This type of analysis is fundamental in statistics and is often the first step in exploring data. Key aspects of univariate analysis include: 1. **Descriptive Statistics**: This involves summarizing and describing the main features of a dataset.

"Up to" can have multiple meanings depending on the context in which it is used. Here are a few common interpretations: 1. **Limit or Capacity**: "Up to" can indicate a maximum limit or capacity. For example, "This elevator can hold up to 10 people" means it cannot hold more than 10 people. 2. **Activity or Responsibility**: It can also refer to being responsible for or engaged in something.

Inequalities are mathematical statements that express the relationship between two expressions that are not necessarily equal to each other. They are used to show that one quantity is greater than, less than, greater than or equal to, or less than or equal to another quantity. The basic symbols used in inequalities include: 1. **Greater than**: \(>\) - Example: \(5 > 3\) (5 is greater than 3) 2.

Probability theorems are fundamental concepts and principles in the field of probability theory, which is the branch of mathematics that deals with the analysis of random phenomena. These theorems help in the understanding, formulation, and calculation of the likelihood of various events occurring.

A compass, in the context of drawing and drafting, is a tool used to create arcs, circles, and angles. It consists of two arms: one with a pointed end (the pivot point) and the other with a pencil or drawing implement attached. By fixing the pointed end at a specific point on paper and rotating the pencil end around that pivot, users can draw accurate circles or portions of circles. Compasses are commonly used in mathematics, geometry, engineering, and various artistic applications.

The Approximate Max-Flow Min-Cut Theorem is a concept in network flow theory, particularly relevant in the context of optimization problems involving flow networks. The theorem relates to the maximum flow that can be sent from a source node to a sink node in a directed graph, and the minimum cut that separates the source from the sink in that graph.

Buchdahl's theorem is a result in general relativity concerning the maximum mass of a spherical, isotropic, perfect fluid star in equilibrium. Specifically, the theorem states that the maximum ratio of a star's mass \( M \) to its radius \( R \) is constrained by: \[ \frac{M}{R} \leq \frac{4}{9} \] when measured in geometrized units (where \( G = c = 1 \)).

Chasles' theorem, in the context of kinematics and rigid body motion, states that any rigid body displacement can be described as a combination of a rotation about an axis and a translation along a vector. This theorem is particularly useful in the analysis of the motion of rigid bodies because it provides a systematic way to break down complex movements into simpler components.

To Brian Josephson for the prediction of the Josephson effect.

The term "Existence Theorem" is commonly used in various fields of mathematics, particularly in analysis, topology, and differential equations. In general, an existence theorem provides conditions under which a certain mathematical object (such as a solution to an equation or a particular structure) actually exists.

The mathematics of apportionment deals with the methods and principles used to allocate seats, resources, or representation among various parties or groups based on certain criteria. It is commonly applied in political elections, allocation of resources, and distribution of goods, ensuring a fair representation or division according to specific rules and mathematical formulas. ### Key Concepts: 1. **Apportionment Methods**: Various mathematical methods exist for apportioning seats or resources.

The Ohsawa–Takegoshi L² extension theorem is a significant result in complex analysis, particularly in the theory of several complex variables. It provides conditions under which holomorphic functions defined on a submanifold can be extended to a larger domain while retaining certain properties, such as being in the L² space. More precisely, the theorem addresses the problem of extending holomorphic functions that are square-integrable on certain subvarieties of complex manifolds.

Calculators are electronic or mechanical devices designed to perform mathematical calculations, ranging from basic arithmetic (addition, subtraction, multiplication, and division) to more complex operations such as trigonometry, logarithms, and calculus. There are several types of calculators, including: 1. **Basic Calculators**: Simple devices that handle basic arithmetic operations. 2. **Scientific Calculators**: These calculators can perform more advanced functions, including trigonometric calculations, exponentiation, and statistical operations.

Stochastic Portfolio Theory (SPT) is a mathematical framework used to analyze portfolio allocations and their performance in a probabilistic context. It combines elements of probability theory, stochastic processes, and financial modeling to understand how portfolios behave over time under uncertainty. The key aspects of SPT include: 1. **Stochastic Processes**: SPT treats asset prices and portfolio returns as stochastic processes, meaning they evolve randomly over time according to certain probabilistic rules.