Equidissection
Equidissection is a mathematical concept related to the idea of dividing shapes into pieces in such a way that the pieces can be rearranged to form another shape of equal area or volume. It involves partitioning a geometric figure into smaller pieces that can be reconfigured without changing their size, typically to demonstrate equivalence in area or volume between different figures. One of the popular contexts for discussing equidissection is in geometry, specifically in polygonal and polyhedral dissections.
The Erdős distinct distances problem, posed by the Hungarian mathematician Paul Erdős in 1946, is a question in combinatorial geometry that seeks to determine the minimum number of distinct distances between points in a given finite set in the plane. Specifically, the problem asks for the largest number of points \( n \) that can be placed in the plane such that the number of distinct distances between pairs of points is minimized.
Erdős–Diophantine graph
The Erdős–Diophantine graph is a concept in graph theory that arises in connection with number theory and combinatorics, particularly focusing on the relationships defined by some Diophantine properties. In this setting, the vertices of the graph typically represent natural numbers or integers, and edges are drawn based on a specific Diophantine condition. The most common version of the Erdős–Diophantine graph considers pairs of integers that satisfy a particular equation or set of equations.
The Hadwiger Conjecture is a significant statement in combinatorial geometry that relates to the coloring of the plane with respect to convex sets, particularly focusing on the properties of regions defined by convex shapes.
Hinged dissection
Hinged dissection is a method in geometry that involves cutting a two-dimensional shape into pieces that can be folded or hinged around common points, allowing the pieces to reconfigure into another shape without overlapping. The concept is often illustrated using paper cutouts, where the cuts create "hinges" at specific points, enabling the pieces to pivot or swing into place. A classic example of hinged dissection is transforming a square into a triangle or vice versa.
Honeycomb conjecture
The Honeycomb Conjecture is a mathematical statement regarding the most efficient way to partition a given area using shapes, specifically focusing on the arrangement of regular hexagons. The conjecture asserts that a regular hexagonal grid provides the most efficient way to divide a plane into regions of equal area with the least perimeter compared to any other shape.
Integer triangle
An "integer triangle" typically refers to a triangle in which the lengths of all three sides are integers. For a triangle to exist with given side lengths, they must satisfy the triangle inequality theorem, which states that for any triangle with sides of lengths \( a \), \( b \), and \( c \): 1. \( a + b > c \) 2. \( a + c > b \) 3.
Integrally convex set
An **integrally convex set** refers to a special type of set in the context of integer programming and combinatorial optimization.
Isosceles set
The term "isosceles set" does not appear to be a widely recognized term in mathematics or any specific field. However, it might be a misinterpretation or a confusion with the term "isosceles triangle," which refers to a triangle that has two sides of equal length.
Kakeya set
A Kakeya set is a set of points in a Euclidean space (typically in two or higher dimensions) that has the property that a needle, or line segment, of unit length can be rotated freely within the set without leaving it. The classic example is the Kakeya set in the plane, which can be thought of as a bounded region that can contain a unit segment that can be rotated to cover all angles.
Kepler conjecture
The Kepler conjecture is a famous problem in the field of discrete mathematics and geometry, specifically concerning the arrangement of spheres. It was proposed by the German mathematician Johannes Kepler in 1611. The conjecture states that no arrangement of spheres (or, more generally, circles or other three-dimensional shapes) can pack more densely than the face-centered cubic (FCC) packing or the hexagonal close packing (HCP).
Kissing number
The "kissing number" refers to the maximum number of non-overlapping spheres that can simultaneously touch another sphere of the same size in a given dimensional space. The concept can be applied in multiple dimensions, and the kissing number varies depending on the dimension. Here are some known kissing numbers: 1. **In 1 dimension**: The kissing number is **2**. A line segment (sphere in 1D) can touch two other line segments at its endpoints.
Kobon triangle problem
The Kobon triangle problem, also known as the "Kobon triangle," is a mathematical problem often discussed in the context of optimization and game theory. However, it seems there might be some confusion since the term "Kobon triangle problem" is not widely recognized in established mathematical literature up to my knowledge cutoff in October 2023.
Lebesgue's universal covering problem is a question in the field of topology, particularly concerning the properties of spaces that can be covered by certain kinds of collections of sets. Specifically, the problem asks whether every bounded measurable set in a Euclidean space can be covered by a countable union of sets of arbitrarily small Lebesgue measure.
The packing constant (or packing density) is a measure of how efficiently a shape can fill space when repeated. Different shapes have various packing constants based on how they can be arranged. Here is a list of some shapes with known packing constants: 1. **Circle**: - Packing Constant: \(\frac{\pi}{\sqrt{12}} \approx 0.9069\) for hexagonal packing 2.
McMullen problem
The McMullen problem, posed by mathematician Curtis T. McMullen in the late 20th century, pertains to the study of hyperbolic 3-manifolds and their geometric structures. Specifically, it concerns the classification of certain types of 3-manifolds known as "hyperbolic 3-manifolds" and the conditions under which these manifolds can be represented as the complement of a knot in S³ (the 3-sphere).
Moser's worm problem
Moser's worm problem is a thought experiment in mathematics and geometry, particularly in the field of topology and combinatorial geometry. It is named after the mathematician Jacob Moser, who posed it in the context of exploring geometric configurations and their properties. The problem can be outlined as follows: Imagine a straight worm of fixed length that can move through a two-dimensional plane.
Moving sofa problem
The Moving Sofa Problem is a classic problem in geometry and mathematical optimization. It involves determining the largest area of a two-dimensional shape (or "sofa") that can be maneuvered around a right-angled corner in a corridor. Specifically, the problem asks for the maximum area of a shape that can be moved around a 90-degree turn in a hallway, where the width of the hallway is fixed.
Napkin folding problem
The Napkin Folding Problem is a classic problem in mathematics and combinatorial geometry, which involves determining the number of distinct ways to fold a napkin, typically represented as a two-dimensional sheet of paper. The goal is to explore how many unique configurations can be created through various folding techniques. The problem can be simplified into analyzing folds along a number of predefined lines, where each fold can change the orientation of the napkin.