Discrete Probability vs VimKata

Everything you need to learn and compute discrete distributions — formulas, derivations, and visual tools, all in one app. In Discrete Probability app, everything is in one place: • User-friendly calculator • Formulas with rigorous yet easy-to-follow derivations — exportable as images or LaTeX • Descriptions of optimized computation methods when they differ from the standard formulas • Histograms and other essential visual tools Covered in the first version: • General concepts with definitions and derivations / proofs • Binomial distribution • Geometric distribution • Negative Binomial distribution • Hypergeometric distribution • Poisson distribution We welcome your feedback — write to graphmath@aol.com

VimKata is a companion app for learning Vim. It teaches you the concepts — what commands exist, how they compose, when to use them. Your physical keyboard builds the muscle memory. Learn in the app, apply in your editor. Every command is demonstrated before you practice it. The buffer animates step by step, a keyboard replica highlights the key being pressed, and a register indicator shows what was stored. You see what a command does before you're expected to use it. A COMPANION, NOT A REPLACEMENT VimKata teaches the mental model. The phone teaches the grammar; the terminal teaches the typing. Pick it up for 10 minutes on a commute, a break, or before bed — then apply what you learned on a real keyboard. DEMO → KATA CYCLE Each exercise starts with an animated demo. A keystroke timeline tracks each step. A MacBook keyboard replica highlights the key. Then you practice on the on-screen keyboard. You never guess — you see it first, then try it. PRACTICE ON REAL CODE Exercises use real JavaScript, Python, HTML, CSS, and Markdown — not toy examples. Each exercise has a concrete editing goal: transform this code into that code. One concept per exercise. SCORE EVERY KEYSTROKE Every exercise produces a grade from S (perfect) to D (keep practicing). After completion, the app shows the optimal solution alongside yours so you can see exactly which command would have been shorter. Retry to improve your grade. 7 LEVELS, 135 EXERCISES - L1: Basic Motions — h j k l w b e 0 $ gg G f t - L2: Basic Editing — x dd dw yy p P cw o - L3: Operators + Motions — de ct df dt ye cc 3w - L4: Text Objects — diw daw ciw ci" da" ci( di( ci{ - L5: Visual Mode — v V d y c ~ o - L6: Navigation Mastery — W B E F T ; , % - L7: Quick Edits — r s J O I D C ^ ~ Levels 1–3 are free. Levels 4–7 unlock with a one-time purchase. Each level has introductory exercises (guided, one command at a time), practice exercises (realistic code, full demo), and challenge exercises (no demo, no hint, tests combined skills). VIM IS A LANGUAGE Most people learn Vim as a list of commands. VimKata teaches you the system underneath — operators compose with motions. Delete a word. Change to end of line. Yank through a character. Once this clicks, you stop memorizing and start composing. BUILD YOUR PRACTICE QUEUE Bookmark exercises for commands you're actively learning. The Saved tab on the home screen gives you quick access to your personal practice list.