The term "V-statistic" typically refers to a specific type of statistical estimator known as a V-statistic, which is a generalization of L-statistics (which are linear combinations of order statistics). V-statistics are particularly useful in the field of non-parametric statistics and are associated with the concept of empirical processes.

A combinatorial proof is a method of proving a mathematical identity or theorem by demonstrating it through a counting argument, often involving the enumeration of sets or counting the same quantity in two different ways. Instead of relying on algebraic manipulations and formal symbolic manipulation, combinatorial proofs use combinatorial arguments to show that two expressions count the same object or quantity.

The Inclusion-Exclusion Principle is a fundamental concept in combinatorics and probability theory that is used to calculate the size of the union of multiple sets when there is overlap between the sets. It provides a systematic way to count the number of elements in the union of several sets by including the sizes of the individual sets and then systematically excluding the sizes of their intersections to avoid over-counting.

Dermott's Law, also known as Dermott's theorem, is a principle in the field of astronomy that deals with the gravitational interactions and the stability of orbits in multi-body systems, particularly in dynamics related to celestial bodies. It provides insights on the behavior of objects under gravitational influence, explaining how bodies in orbit can affect each other's motions and stability over time. The law highlights specific aspects of orbital mechanics that are crucial for understanding the dynamics of planetary systems, moons, and other celestial configurations.

The Bonnor–Ebert mass refers to a critical mass threshold for a stable, isothermal cloud of gas in astrophysics. This concept is important in the study of star formation and the stability of molecular clouds. The Bonnor–Ebert mass is derived from the work of the astrophysicists William Bonnor and Erwin Ebert in the early 20th century.

The matrix sign function is a matrix-valued function that generalizes the scalar sign function to matrices. For a square matrix \( A \), the matrix sign function, denoted as \( \text{sign}(A) \), is defined in terms of the eigenvalues of the matrix.

The Moffat distribution is a statistical distribution used primarily in the fields of astrophysics and image processing. It is often employed to model the point spread function (PSF) of optical systems, especially in the context of astronomical observations. The Moffat function is characterized by its ability to describe the spread of light from a point source, allowing for a profile that has more pronounced "wings" compared to Gaussian functions, which decay more rapidly.

The Sigma-D relation, also known as the \(\Sigma-D\) relation or the \(\Sigma-D\) correlation, is a concept in astrophysics and cosmology that describes a relationship between the surface density of galaxies (or their stellar components) and their dynamical properties, particularly their rotational velocity or other measures of mass distribution.