Introduction General Definitions When can any weight function be turned into a strictly monotone weight function? Weighted Directed Graphs in Applications Autonomous Driving Quantum Walks Artificial Neural Networks SUMMARY: We define a directed graph as a space with any binary relation, and we define a strictly monotone weight function on any directed graph. We prove when no weight function on a directed graph can be turned into a strictly monotone weight function, and we give a characterization of any strictly monotone weight function. Finally, we mention the use of weighted directed graphs in autonomous driving research, quantum information, and deep learning. Introduction Here is an example of a…


Topological Manifolds
Introduction A generalization to infinite dimension Is there any relationship between an infinitedimensional manifold and a finitedimensional manifold? Manifolds in applications Infection dynamics Topological data analysis Riemannian manifold optimization software library SUMMARY: We define a manifold of an infinite dimension, which is an extension of a finitedimensional manifold, and we show in what sense an infinitedimensional manifold is related to any finitedimensional manifold. We then mention the use of manifolds in applications. Introduction Given any point $x$ on the surface of a sphere and any circle drawn around $x$, the region inside the circle approaches the shape of a 2dimensional ``flat'' disk as the circle gets smaller. The surface of…

Two Notions of an Infinite Chain in a Directed Graph
Introduction Definitions Directed Graphs Infinite Chains (Def. 1 & Def. 2) When are Def. 1 and Def. 2 equivalent? A fix with the axiom of countable choice Directed Graphs in Applications Softwares Graph Neural Networks Quantum Information SUMMARY: We introduce two notions of an infinite chain in a directed graph, and we show when these two notions are equivalent. We then mention the use of directed graphs in applications, such as artificial intelligence and quantum information. Introduction Consider this diagram \[ \begin{array}{ccccc} \bullet & \rightarrow & \bullet\\ \downarrow & & \downarrow\\ \bullet & \rightarrow & \bullet & \rightarrow & \bullet \end{array} \] which consists of vertices (the dots) and arrows…

The Tensor Product: from vector spaces to categories
Introduction General Definition The tensor product is not the same as the Cartesian product A jump to categories Applications TensorFlow Artificial Intelligence Quantum Optics SUMMARY: We show why the tensor product is not the same as the Cartesian product, and we extend that result to categories. We then mention the use of the tensor product in applications, such as artificial intelligence and quantum optics. Introduction For any vectors $\left\langle x_{1},x_{2}\right\rangle $ of $\mathbb{R}^{2}$ and $\left\langle y_{1},y_{2},y_{3}\right\rangle $ of $\mathbb{R}^{3}$, a product of these two vectors, which is denoted as $\left\langle x_{1},x_{2}\right\rangle \otimes\left\langle y_{1},y_{2},y_{3}\right\rangle $, is defined as the matrix \[ \left[\begin{array}{ccc} x_{1}y_{1} & x_{1}y_{2} & x_{1}y_{_{3}}\\ x_{2}y_{1} & x_{2}y_{2} &…

A Generalization of Convex Sets and Convex Functions
Introduction The setting: a vector space over a field with a partial order A Convex set is the same as an orderconvex set A convex function defined in terms of a convex set A convex function in terms of orderconvexity Convex sets and convex functions in machine learning Convex Optimization Software Libraries SUMMARY: We define a convex set in a general framework of a vector space over a field with a partial order, and we show how the general notion is related to the usual notion of a convex set. Then we define a convex function in terms of that general notion of a convex set, and we show…

The Rank of a Matrix with some Association with Machine Learning and Quantum Computing
Introduction General Definition Some results involving the rank of a matrix Theorem 5.1 (Ivanyos et al., 2018) Lemma 5.2 (Ivanyos et al., 2018) Rank of a matrix in machine learning Lowrank matrix approximation Apache Spark: a computer framework for matrix computation Rank of a matrix in quantum information Kraus Operators Introduction (back to outline) For a matrix \[A=\left[\begin{array}{ccc}0 & 1 & 1\\1 & 2 & 1\\1 & 1 & 3\end{array}\right],\] where each entry is a real number, the columns of $A$ form a linearly independent set of vectors of $\mathbb{R}^{3}$, so the subspace generated by the three columns is of dimension $3$, which is isomorphic to $\mathbb{R}^{3}$. The dimension…

On Teaching Trigonometry: Graphing Trigonometric Functions (Part 2)
Note: Thoughts expressed in this article are solely those of the author(s). Any advice given in this article may not work in all situations. SUMMARY: We talk about how you can show your students to program a computer to graph trigonometric functions. We use the Python programming language as an example. If you need to see Part 1 of this article, you can access it here. Showing your students how to graph trigonometric functions, using different techniques, can be fun. Besides using softwares, you can show your students how to program a computer to graph trigonometric functions. Programming a computer to graph trigonometric functions Again, we think…

On Teaching Trigonometry: Graphing Trigonometric Functions (Part 1)
Note: Thoughts expressed in this article are solely those of the author(s). Any advice given in this article may not work in all situations. SUMMARY: We talk about how to introduce your students to graphing trigonometric functions. After you’ve explained to your students that the sine and cosine are functions from the real numbers to the real numbers, you may need to mention that the tangent, cotangent, secant, and cosecant are also functions of a real variable but that are undefined for some real numbers. Explain to them the reason for the undefinedness: these last four functions are defined as ratios, where their denominators are variables, which cannot…

On Teaching Trigonometry: Trigonometric Functions and the Unit Circle
Note: Thoughts expressed in this article are solely those of the author(s). Any advice given in this article may not work in all situations. SUMMARY: We talk about how to introduce your students to the general notion of a trigonometric function defined for any angle, acute or not, and we talk about how to use the unit circle to define trigonometric functions. After you’ve spent some time practicing with your students and give them some time to work on exercises on their own, you may need to move on to other topics. Now that you’re done working with evaluating trigonometric functions on an acute angle, it’s probably…

On Teaching Trigonometry: Angles and the Right Triangle
Note: Thoughts expressed in this article are solely those of the author(s). Any advice given in this article may not work in all situations. SUMMARY: We talk about how to start introducing your students to the trigonometry of the right triangle and to remind them of the importance of practice. By now, many of your students may be all excited about trigonometry. You’ve managed to persuade them that it is worth to put the efforts to comprehend the technicalities that you will explain to them. But you will also need to remind them of the importance of prerequisite knowledge. To effectively communicate the technicalities to your students,…