**The Story of Math Academy’s Eurisko Sequence **

2023 Feb | During its operation from 2020 to 2023, Eurisko was one of the most advanced high school math/CS sequences in the USA.

Posts

## 2023

**Selecting a Good Problem to Work On **

2023 Jan | Good problem = intersection between your own interests/talents, the realm of what's feasible, and the desires of the external world.

## 2022

**From Procedures to Objects **

2022 Dec | An aha moment with object-oriented programming.

**Quants vs Systems Coders **

2022 Oct | Two subtypes of coders that I watched students grow into.

**Tips for Developing Valuable Models **

2022 Oct | Stuff you don't find in math textbooks.

**The 5 Breeds of Quants **

2022 Aug | ... are summarized in the following table.

**Reimplementing Blondie24: Convolutional Version **

2022 Mar | Using convolutional layers to create an even better checkers player.

**Reimplementing Blondie24 **

2022 Mar | Extending Fogel's tic-tac-toe player to the game of checkers.

**Reimplementing Fogel’s Tic-Tac-Toe Paper **

2022 Mar | Reimplementing the paper that laid the groundwork for Blondie24.

**Introduction to Blondie24 and Neuroevolution **

2022 Mar | A method for training neural networks that works even when training feedback is sparse.

**Reduced Search Depth and Heuristic Evaluation for Connect Four **

2022 Mar | Combining game-specific human intelligence (heuristics) and generalizable artificial intelligence (minimax on a game tree)

**Minimax Strategy **

2022 Mar | Repeatedly choosing the action with the best worst-case scenario.

**Canonical and Reduced Game Trees for Tic-Tac-Toe **

2022 Mar | Building data structures that represent all the possible outcomes of a game.

**Backpropagation **

2022 Feb | A convenient technique for computing gradients in neural networks.

**Introduction to Neural Network Regressors **

2022 Feb | The deeper or more "hierarchical" a computational graph is, the more complex the model that it represents.

**Decision Trees **

2022 Feb | We can algorithmically build classifiers that use a sequence of nested "if-then" decision rules.

**Dijkstra’s Algorithm for Distance and Shortest Paths in Weighted Graphs **

2022 Feb | Computing spatial relationships between nodes when edges no longer represent unit distances.

**Distance and Shortest Paths in Unweighted Graphs **

2022 Feb | Using traversals to understand spatial relationships between nodes in graphs.

**Breadth-First and Depth-First Traversals **

2022 Feb | Graphs show up all the time in computer science, so it's important to know how to work with them.

**Naive Bayes **

2022 Jan | A simple classification algorithm grounded in Bayesian probability.

**K-Nearest Neighbors **

2022 Jan | One of the simplest classifiers.

**Multiple Regression and Interaction Terms **

2022 Jan | In many real-life situations, there is more than one input variable that controls the output variable.

**Regression via Gradient Descent **

2022 Jan | Gradient descent can help us avoid pitfalls that occur when fitting nonlinear models using the pseudoinverse.

**Overfitting, Underfitting, Cross-Validation, and the Bias-Variance Tradeoff **

2022 Jan | Just because model appears to match closely with points in the data set, does not necessarily mean it is a good model.

**Power, Exponential, and Logistic Regression via Pseudoinverse **

2022 Jan | Transforming nonlinear functions so that we can fit them using the pseudoinverse.

**Regressing a Linear Combination of Nonlinear Functions via Pseudoinverse **

2022 Jan | Exploring the most general class of functions that can be fit using the pseudoinverse.

**Linear, Polynomial, and Multiple Linear Regression via Pseudoinverse **

2022 Jan | Using matrix algebra to fit simple functions to data sets.

## 2021

**Simplex Method **

2021 Mar | A technique for maximizing linear expressions subject to linear constraints.

**Hash Tables **

2021 Mar | Under the hood, dictionaries are hash tables.

**Hodgkin-Huxley Model of Action Potentials in Neurons **

2021 Mar | Implementing a differential equations model that won the Nobel prize.

**SIR Model For the Spread of Disease **

2021 Mar | A simple differential equations model that we can plot using multivariable Euler estimation.

**Euler Estimation **

2021 Mar | Arrays can be used to implement more than just matrices. We can also implement other mathematical procedures like Euler estimation.

**Tic-Tac-Toe and Connect Four **

2021 Mar | One of the best ways to get practice with object-oriented programming is implementing games.

**K-Means Clustering **

2021 Mar | Guess some initial clusters in the data, and then repeatedly update the guesses to make the clusters more cohesive.

**Reduced Row Echelon Form and Applications to Matrix Arithmetic **

2021 Mar | You can use the RREF algorithm to compute determinants much faster than with the recursive cofactor expansion method.

**Basic Matrix Arithmetic **

2021 Mar | We can use arrays to implement matrices and their associated mathematical operations.

**The Ultimate High School Computer Science Sequence: 9 Months In **

2021 Feb | In 9 months, these students went from initially not knowing how to write helper functions to building a machine learning library from scratch.

**Merge Sort and Quicksort **

2021 Feb | Merge sort and quicksort are generally faster than selection, bubble, and insertion sort. And unlike counting sort, they are not susceptible to blowup in the amount of memory required.

**Selection, Bubble, Insertion, and Counting Sort **

2021 Feb | Some of the simplest methods for sorting items in arrays.

**Multivariable Gradient Descent **

2021 Feb | Just like single-variable gradient descent, except that we replace the derivative with the gradient vector.

**Single-Variable Gradient Descent **

2021 Feb | We take an initial guess as to what the minimum is, and then repeatedly use the gradient to nudge that guess further and further "downhill" into an actual minimum.

**Estimating Roots via Bisection Search and Newton-Raphson Method **

2021 Feb | Bisection search involves repeatedly moving one bound halfway to the other. The Newton-Raphson method involves repeatedly moving our guess to the root of the tangent line.

**Solving Magic Squares via Backtracking **

2021 Feb | Backtracking can drastically cut down the number of possibilities that must be checked during brute force.

**Brute Force Search with Linear-Encoding Cryptography **

2021 Feb | Brute force search involves trying every single possibility.

**Cartesian Product **

2021 Jan | Implementing the Cartesian product provides good practice working with arrays.

**Roulette Wheel Selection **

2021 Jan | How to sample from a discrete probability distribution.

**Simulating Coin Flips **

2021 Jan | Estimating probabilities by simulating a large number of random experiments.

**Recursive Sequences **

2021 Jan | Sequences where each term is a function of the previous terms.

**Converting Between Binary, Decimal, and Hexadecimal **

2021 Jan | There are other number systems that use more or fewer than ten characters.

**Some Short Introductory Coding Exercises **

2021 Jan | It's assumed that you've had some basic exposure to programming.

## 2020

**Tips for LaTeX Math Formatting **

2020 Sep | How to avoid some of the most common pitfalls leading to ugly LaTeX.

## 2019

**Path Dependency in Multivariable Limits **

2019 Dec | The behavior of a multivariable function can be highly specific to the path taken.

**Thales’ Theorem **

2019 Dec | Every inscribed triangle whose hypotenuse is a diameter is a right triangle.

**But WHERE do the Taylor Series and Lagrange Error Bound even come from?! **

2019 Dec | An intuitive derivation.

**Trick to Apply the Chain Rule FAST - Peeling the Onion **

2019 Dec | A simple mnemonic trick for quickly differentiating complicated functions.

**Intuition Behind Completing the Square **

2019 Dec | Hidden inside of every quadratic, there is a perfect square.

**Matrix Exponential and Systems of Linear Differential Equations **

2019 Sep | The matrix exponential can be defined as a power series and used to solve systems of linear differential equations.

**Generalized Eigenvectors and Jordan Form **

2019 Sep | Jordan form provides a guaranteed backup plan for exponentiating matrices that are non-diagonalizable.

**Recursive Sequence Formulas via Diagonalization **

2019 Sep | Matrix diagonalization can be applied to construct closed-form expressions for recursive sequences.

**Eigenvalues, Eigenvectors, and Diagonalization **

2019 Sep | The eigenvectors of a matrix are those vectors that the matrix simply rescales, and the factor by which an eigenvector is rescaled is called its eigenvalue. These concepts can be used to quickly calculate large powers of matrices.

**Inverse Matrices **

2019 Aug | The inverse of a matrix is a second matrix which undoes the transformation of the first matrix.

**Rescaling, Shearing, and the Determinant **

2019 Aug | Every square matrix can be decomposed into a product of rescalings and shears.

**Matrix Multiplication **

2019 Aug | How to multiply a matrix by another matrix.

**Linear Systems as Transformations of Vectors by Matrices **

2019 Aug | Matrices are vectors whose components are themselves vectors.

**Higher-Order Variation of Parameters **

2019 Jul | Solving linear systems can sometimes be a necessary component of solving nonlinear systems.

**Shearing, Cramer’s Rule, and Volume by Reduction **

2019 Jul | Shearing can be used to express the solution of a linear system using ratios of volumes, and also to compute volumes themselves.

**Volume as the Determinant of a Square Linear System **

2019 Jul | Rich intuition about why the number of solutions to a square linear system is governed by the volume of the parallelepiped formed by the coefficient vectors.

**N-Dimensional Volume Formula **

2019 Jul | N-dimensional volume generalizes the idea of the space occupied by an object. We can think about N-dimensional volume as being enclosed by N-dimensional vectors.

**Elimination as Vector Reduction **

2019 Jun | If we interpret linear systems as sets of vectors, then elimination corresponds to vector reduction.

**Span, Subspaces, and Reduction **

2019 Jun | The span of a set of vectors consists of all vectors that can be made by adding multiples of vectors in the set. We can often reduce a set of vectors to a simpler set with the same span.

**Lines and Planes **

2019 Jun | A line starts at an initial point and proceeds straight in a constant direction. A plane is a flat sheet that makes a right angle with some particular vector.

**Dot Product and Cross Product **

2019 Jun | What does it mean to multiply a vector by another vector?

**N-Dimensional Space **

2019 Jun | N-dimensional space consists of points that have N components.

**CheckMySteps: A Web App to Help Students Fix their Algebraic Mistakes **

2019 May | A prototype web app to automatically assist students in self-correcting small errors and minor misconceptions.

**Solving Tower of Hanoi with General Problem Solver **

2019 May | A walkthrough of solving Tower of Hanoi using the approach of one of the earliest AI systems.

**Cutting Through the Hype of AI **

2019 May | Media outlets often make the mistake of anthropomorphizing or attributing human-like characteristics to computer programs.

**The Third Wave of AI: Computation Power and Neural Networks **

2019 May | As computation power increased, neural networks began to take center stage in AI.

**The Second Wave of AI: Expert Systems **

2019 May | Expert systems stored "if-then" rules derived from the knowledge of experts.

**The First Wave of AI: Reasoning as Search **

2019 May | Framing reasoning as searching through a maze of actions for a sequence that achieves the desired end goal.

**What is AI? **

2019 May | Turing test, games, hype, narrow vs general AI.

**Introductory Python: Functions **

2019 May | Rather than duplicating such code each time we want to use it, it is more efficient to store the code in a function.

**Introductory Python: If, While, and For **

2019 May | We often wish to tell the computer instructions involving the words "if," "while," and "for."

**Introductory Python: Lists, Dictionaries, and Arrays **

2019 May | We can store many related pieces of data within a single variable called a data structure.

**Introductory Python: Strings, Ints, Floats, and Booleans **

2019 May | We can store and manipulate data in the form of variables.

**Graphing Calculator Drawing: Composition Waves and Implicit Trig Patterns **

2019 May | Equations involving compositions of trigonometric functions can create wild patterns in the plane.

**Graphing Calculator Drawing: Lissajous Curves **

2019 May | Lissajous curves use sine functions to create interesting patterns in the plane.

**Graphing Calculator Drawing: Rotation **

2019 May | Absolute value graphs can be rotated to draw stars.

**Graphing Calculator Drawing: Non-Euclidean Ellipses **

2019 May | Non-euclidean ellipses can be used to draw starry-eye sunglasses.

**Graphing Calculator Drawing: Euclidean Ellipses **

2019 May | Euclidean ellipses can be combined with sine wave shading to form three-dimensional shells.

**Graphing Calculator Drawing: Shading with Sine **

2019 May | High-frequency sine waves can be used to draw shaded regions.

**Graphing Calculator Drawing: Roots **

2019 May | Roots can be used to draw deer.

**Graphing Calculator Drawing: Sine Waves **

2019 May | Sine waves can be used to draw scales on a fish.

**Graphing Calculator Drawing: Parabolas **

2019 May | Parabolas can be used to draw a fish.

**Graphing Calculator Drawing: Absolute Value **

2019 May | Absolute value can be used to draw a person.

**Graphing Calculator Drawing: Slanted Lines **

2019 May | Slanted lines can be used to draw a spider web.

**Graphing Calculator Drawing: Horizontal and Vertical Lines **

2019 May | Horizontal and vertical lines can be used to draw a castle.

**Solving Differential Equations with Taylor Series **

2019 Apr | Many differential equations don't have solutions that can be expressed in terms of finite combinations of familiar functions. However, we can often solve for the Taylor series of the solution.

**Manipulating Taylor Series **

2019 Apr | To find the Taylor series of complicated functions, it's often easiest to manipulate the Taylor series of simpler functions.

**Taylor Series **

2019 Apr | Many non-polynomial functions can be represented by infinite polynomials.

**Tests for Convergence **

2019 Apr | Various tricks for determining whether a series converges or diverges.

**Geometric Series **

2019 Apr | A geometric series is a sum where each term is some constant times the previous term.

**Variation of Parameters **

2019 Mar | When we know the solutions of a linear differential equation with constant coefficients and right hand side equal to zero, we can use variation of parameters to find a solution when the right hand side is not equal to zero.

**Integrating Factors **

2019 Mar | Integrating factors can be used to solve first-order differential equations with non-constant coefficients.

**Undetermined Coefficients **

2019 Mar | Undetermined coefficients can help us find a solution to a linear differential equation with constant coefficients when the right hand side is not equal to zero.

**Characteristic Polynomial of a Differential Equation **

2019 Mar | Given a linear differential equation with constant coefficients and a right hand side of zero, the roots of the characteristic polynomial correspond to solutions of the equation.

**Solving Differential Equations by Substitution **

2019 Mar | Non-separable differential equations can be sometimes converted into separable differential equations by way of substitution.

**Slope Fields and Euler Approximation **

2019 Mar | When faced with a differential equation that we don't know how to solve, we can sometimes still approximate the solution.

**Separation of Variables **

2019 Mar | The simplest differential equations can be solved by separation of variables, in which we move the derivative to one side of the equation and take the antiderivative.

**Improper Integrals **

2019 Feb | Improper integrals have bounds or function values that extend to positive or negative infinity.

**Integration by Parts **

2019 Feb | We can apply integration by parts whenever an integral would be made simpler by differentiating some expression within the integral, at the cost of anti-differentiating another expression within the integral.

**Integration by Substitution **

2019 Feb | Substitution involves condensing an expression of into a single new variable, and then expressing the integral in terms of that new variable.

**Finding Area Using Integrals **

2019 Feb | To evaluate a definite integral, we find the antiderivative, evaluate it at the indicated bounds, and then take the difference.

**Antiderivatives **

2019 Feb | The antiderivative of a function is a second function whose derivative is the first function.

**L’Hôpital’s Rule **

2019 Jan | When a limit takes the indeterminate form of zero divided by zero or infinity divided by infinity, we can differentiate the numerator and denominator separately without changing the actual value of the limit.

**Differentials and Approximation **

2019 Jan | We can interpret the derivative as an approximation for how a function's output changes, when the function input is changed by a small amount.

**Finding Extrema **

2019 Jan | Derivatives can be used to find a function's local extreme values, its peaks and valleys.

**Derivatives of Non-Polynomial Functions **

2019 Jan | There are convenient rules the derivatives of exponential, logarithmic, trigonometric, and inverse trigonometric functions.

**Properties of Derivatives **

2019 Jan | Given a sum, we can differentiate each term individually. But why are we able to do this? Does multiplication work the same way? What about division?

**Chain Rule **

2019 Jan | When taking derivatives of compositions of functions, we can ignore the inside of a function as long as we multiply by the derivative of the inside afterwards.

**Power Rule for Derivatives **

2019 Jan | There are some patterns that allow us to compute derivatives without having to compute the limit of the difference quotient.

**Derivatives and the Difference Quotient **

2019 Jan | The derivative of a function is the function's slope at a particular point, and can be computed as the limit of the difference quotient.

**Limits by Logarithms, Squeeze Theorem, and Euler’s Constant **

2019 Jan | Various tricks for evaluating tricky limits.

**Evaluating Limits **

2019 Jan | The limit of a function, as the input approaches some value, is the output we would expect if we saw only the surrounding portion of the graph.

## 2018

**Compositions of Functions **

2018 Jul | Compositions of functions consist of multiple functions linked together, where the output of one function becomes the input of another function.

**Inverse Functions **

2018 Jul | Inverting a function entails reversing the outputs and inputs of the function.

**Reflections of Functions **

2018 Jul | When a function is reflected, it flips across one of the axes to become its mirror image.

**Rescalings of Functions **

2018 Jul | When a function is rescaled, it is stretched or compressed along one of the axes, like a slinky.

**Shifts of Functions **

2018 Jul | When a function is shifted, all of its points move vertically and/or horizontally by the same amount.

**Piecewise Functions **

2018 Jun | A piecewise function is pieced together from multiple different functions.

**Trigonometric Functions **

2018 Jun | Trigonometric functions represent the relationship between sides and angles in right triangles.

**Absolute Value **

2018 Jun | Absolute value represents the magnitude of a number, i.e. its distance from zero.

**Exponential and Logarithmic Functions **

2018 Jun | Exponential functions have variables as exponents. Logarithms cancel out exponentiation.

**Radical Functions **

2018 Jun | Radical functions involve roots: square roots, cube roots, or any kind of fractional exponent in general.

**Graphing Rational Functions with Slant and Polynomial Asymptotes **

2018 May | A slant asymptote is a slanted line that arises from a linear term in the proper form of a rational function.

**Graphing Rational Functions with Horizontal and Vertical Asymptotes **

2018 May | If we choose one input on each side of an asymptote, we can tell which section of the plane the function will occupy.

**Vertical Asymptotes of Rational Functions **

2018 May | Vertical asymptotes are vertical lines that a function approaches but never quite reaches.

**Horizontal Asymptotes of Rational Functions **

2018 May | Rational functions can have a form of end behavior in which they become flat, approaching (but never quite reaching) a horizontal line known as a horizontal asymptote.

**Polynomial Long Division **

2018 May | Polynomial long division works the same way as the long division algorithm that's familiar from simple arithmetic.

**Sketching Graphs of Polynomials **

2018 Apr | We can sketch the graph of a polynomial using its end behavior and zeros.

**Rational Roots and Synthetic Division **

2018 Apr | The rational roots theorem can help us find zeros of polynomials without blindly guessing.

**Zeros of Polynomials **

2018 Apr | The zeros of a polynomial are the inputs that cause it to evaluate to zero.

**Standard Form and End Behavior of Polynomials **

2018 Apr | The end behavior of a polynomial refers to the type of output that is produced when we input extremely large positive or negative values.

**Systems of Inequalities **

2018 Mar | To solve a system of inequalities, we need to solve each individual inequality and find where all their solutions overlap.

**Quadratic Inequalities **

2018 Mar | Quadratic inequalities are best visualized in the plane.

**Linear Inequalities in the Plane **

2018 Mar | When a linear equation has two variables, the solution covers a section of the coordinate plane.

**Linear Inequalities in the Number Line **

2018 Mar | An inequality is similar to an equation, but instead of saying two quantities are equal, it says that one quantity is greater than or less than another.

**Quadratic Systems **

2018 Feb | Systems of quadratic equations can be solved via substitution.

**Vertex Form **

2018 Feb | To easily graph a quadratic equation, we can convert it to vertex form.

**Completing the Square **

2018 Feb | Completing the square helps us gain a better intuition for quadratic equations and understand where the quadratic formula comes from.

**Quadratic Formula **

2018 Feb | To solve hard-to-factor quadratic equations, it's easiest to use the quadratic formula.

**Factoring Quadratic Equations **

2018 Feb | Factoring is a method for solving quadratic equations.

**Standard Form of a Quadratic Equation **

2018 Feb | Quadratic equations are similar to linear equations, except that they contain squares of a single variable.

**Linear Systems **

2018 Feb | A linear system consists of multiple linear equations, and the solution of a linear system consists of the pairs that satisfy all of the equations.

**Standard Form of a Line **

2018 Feb | Standard form makes it easy to see the intercepts of a line.

**Point-Slope Form **

2018 Feb | An easy way to write the equation of a line if we know the slope and a point on a line.

**Slope-Intercept Form **

2018 Feb | Introducing linear equations in two variables.

**Solving Linear Equations **

2018 Feb | Loosely speaking, a linear equation is an equality statement containing only addition, subtraction, multiplication, and division.

**Intuiting Ensemble Methods **

2018 Jan | The type of ensemble model that wins most data science competitions is the stacked model, which consists of an ensemble of entirely different species of models together with some combiner algorithm.

**Intuiting Decision Trees **

2018 Jan | Decision trees are able to model nonlinear data while remaining interpretable.

**Intuiting Neural Networks **

2018 Jan | NNs are similar to SVMs in that they project the data to a higher-dimensional space and fit a hyperplane to the data in the projected space. However, whereas SVMs use a predetermined kernel to project the data, NNs automatically construct their own projection.

**Intuiting Support Vector Machines **

2018 Jan | A Support Vector Machine (SVM) computes the "best" separation between classes as the maximum-margin hyperplane.

**Intuiting Linear Regression **

2018 Jan | In linear regression, we model the target as a random variable whose expected value depends on a linear combination of the predictors (including a bias term).

**Intuiting Maximum a Posteriori and Maximum Likelihood Estimation **

2018 Jan | To visualize the relationship between the MAP and MLE estimations, one can imagine starting at the MLE estimation, and then obtaining the MAP estimation by drifting a bit towards higher density in the prior distribution.

**Intuiting Naive Bayes **

2018 Jan | Naive Bayes classification naively assumes that the presence of a particular feature in a class is unrelated to the presence of any other feature.

## 2017

**Applications of Calculus: Calculating the Horsepower of an Offensive Lineman **

2017 Nov | It comes out to roughly a fortieth of that of a truck.

**Applications of Calculus: Derivatives in String Art **

2017 Nov | String art works because the strings are tangent lines to a curve.

**Applications of Calculus: A Failure of Intuition **

2017 Nov | Calculus can show us how our intuition can fail us, a common theme in philosophy.

**History of Calculus: The Newton-Leibniz Controversy **

2017 Nov | Nobody came out of the dispute well.

**History of Calculus: The Man who “Broke” Math **

2017 Nov | When Joseph Fourier first introduced Fourier series, they gave mathematicians nightmares.

**Applications of Calculus: Continuously Compounded Interest **

2017 Nov | Deriving the "Pert" formula.

**Applications of Calculus: Maximizing Profit **

2017 Nov | If we know the revenue and costs associated with producing any number of units, then we can use calculus to figure out the number of units to produce for maximum profit.

**Applications of Calculus: Optimization via Gradient Descent **

2017 Nov | Calculus can be used to find the parameters that minimize a function.

**Applications of Calculus: Physics Engines in Video Games **

2017 Nov | Physics engines use calculus to periodically updates the locations of objects.

**Applications of Calculus: Rendering 3D Computer Graphics **

2017 Nov | Introducing Kajiya's rendering equation.

**Applications of Calculus: Rocket Propulsion **

2017 Nov | Deriving the ideal rocket equation.

**Applications of Calculus: Modeling Tumor Growth **

2017 Nov | Deriving the Gompertz function.

**Applications of Calculus: Understanding Plaque Buildup **

2017 Nov | Understanding why even slight narrowing of arteries can pose such a big problem to blood flow.

**Applications of Calculus: Cardiac Output **

2017 Nov | Measuring volume of blood the heart pumps out into the aorta per unit time.

**Intuiting Series **

2017 Oct | A series is the sum of a sequence.

**Intuiting Sequences **

2017 Oct | A sequence is a list of numbers that has some pattern.

**Intuiting Integrals **

2017 Oct | Integrals give the area under a portion of a function.

**Intuiting Derivatives **

2017 Oct | The derivative tells the steepness of a function at a given point, kind of like a carpenter's level.

**Intuiting Limits **

2017 Oct | The limit of a function is the height where it looks like the scribble is going to hit a particular vertical line.

**Intuiting Functions **

2017 Oct | A function is a scribble that crosses each vertical line only once.

**The Data Scientist’s Guide to Topological Data Analysis: Preamble **

2017 Sep | Bridging the communication gap between academia and industry in the field of TDA.

**Persistent Homology Software: Demonstration of TDA **

2017 Sep | Demonstrating an open-source implementation of persistent homology techniques in the TDA package for R.

**Intuiting Persistent Homology **

2017 Sep | Persistent homology provides a way to quantify the topological features that persist over our a data set's full range of scale.

**Mapper Use-Cases at Aunalytics **

2017 Sep | At Aunalytics, Mapper outperformed hierarchical clustering in providing granular insights.

**Mapper Use-Cases at Ayasdi **

2017 Sep | Ayasdi developed commercial Mapper software and sells a subscription service to clients who wish to create topological network visualizations of their data.

**Mapper Software: Demonstration of TDAmapper **

2017 Sep | Demonstrating an open-source implementation of Mapper in the TDAmapper package for R.

**Intuiting the Mapper Algorithm **

2017 Sep | Representing a data space's topology by converting it into a network.

## 2016

**A Game-Theoretic Analysis of Social Distancing During Epidemics **

2016 May | In a simplified problem framing, we investigate the (theoretical) usefulness of limiting the number of social connections per person.

**Making Indirect Interactions Explicit in Networks **

2016 Mar | Category theory provides a language for explicitly describing indirect relationships in graphs.

**Book Summary: Memory Evolutive Systems **

2016 Mar | Framing complex systems in the language of category theory.

## 2015

**Introduction to Computers **

2015 Nov | The main ideas behind computers can be understood by anyone.

**The Brain in One Sentence **

2015 Nov | The brain is a neuronal network integrating specialized subsystems that use local competition and thresholding to sparsify input, spike-timing dependent plasticity to learn inference, and layering to implement hierarchical predictive learning.

**Shaping STDP Neural Networks with Periodic Stimulation: a Theoretical Analysis for the Case of Tree Networks **

2015 Aug | We solve a special case of how to periodically stimulate a neural network to obtain a desired connectivity.

**A Visual, Inductive Proof of Sharkovsky’s Theorem **

2015 Jan | Many existing proofs are not accessible to young mathematicians or those without experience in the realm of dynamic systems.

## 2014

**The Physics Behind an Egg Drop: A Lively Story **

2014 Jun | Escaping a troll by using its own weight against itself.

## 2013

**A Formula for the Partial Fractions Decomposition of $x^n/(x-a)^k$ **

2013 Aug | And a proof via double induction.

**Sound Waves **

2013 May | A brief overview of sound waves and how they interact with things.

**Detecting Dark Matter **

2013 May | A brief overview of the experimental search for dark matter (XENON, CDMS, PICASSO, COUPP).

**Evidence for the Existence of Dark Matter **

2013 May | Mass discrepancies in galaxies and clusters, cosmic background radiation, the structure of the universe, and big bang nucleosynthesis's impact on baryon density.