EntCSExplore. Visualise. Understand.

Everything on the site.

Big-O notationAlgorithms · Count the steps in real loops, then compare n, n log n, n² and 2ⁿ on a live chart.RecursionAlgorithms · Watch frames push and pop on the call stack for factorial and Fibonacci.BFS vs DFSAlgorithms · A queue against a stack: draw a graph and see which order each search visits it in.Sorting algorithmsAlgorithms · Seven sorts on the same input, with comparison, swap and write counts side by side.Binary searchAlgorithms · Halve the range, probe the middle, repeat: with lo, mid and hi drawn on the array.Sets, relations and functionsDiscrete maths · Shade any set expression on a Venn diagram and test a relation for its properties.Proof by inductionDiscrete maths · Four worked proofs revealed one step at a time, and a broken one to diagnose.CombinatoricsDiscrete maths · An exact nPr and nCr calculator, and a Pascal’s triangle that shows its own addition rule.Boolean algebraDiscrete maths · The laws, De Morgan, and normal forms, with a truth-table generator built in.Finite-state machinesTheory · Build a DFA in a table, see it drawn, and run strings through it one symbol at a time.Domain theoryTheory · Why recursion needs least fixed points, and how CPOs, Scott continuity and powerdomains supply them.Truth table generatorTools · Expression in, truth table out: with DNF, CNF, a minimal form and LaTeX.Graph traversal visualiserTools · Draw a graph, then animate BFS, DFS and Dijkstra with the frontier shown.Recursion tree visualiserTools · Paste a recursive function or a recurrence and see its call tree and call count.Gradient descentML maths · Drag the starting point, set the learning rate, and watch it converge or blow up.Vectors and embeddingsML maths · Bend the plane with a 2×2 matrix and measure how close toy word vectors are.Softmax and cross-entropyML maths · Edit the logits and watch the probabilities, the loss and the gradient update live.AttentionML maths · Q, K and V for three tokens, a live score heatmap, and the weighted sum of values.Formatting a CS paper in LaTeXLaTeX · Page limits, \documentclass, front matter, theorem environments and the bibliography.Camera-ready checklistLaTeX · Fonts embedded, PDF/A, copyright form, source bundle, and why final versions get rejected.LaTeX templatesLaTeX · Where the official classes live, plus a minimal article template you can copy.AlgorithmsSection · Step-through visualisations of sorting, searching, recursion, graph traversal and Big-O growth, each with pseudocode that highlights the line being run.Discrete mathsSection · Sets, relations and functions, proof by induction, counting, and Boolean algebra, explained with worked examples and small interactive checkers.TheorySection · Finite-state machines, automata and the mathematical semantics of programming languages, explained from first principles.ML mathsSection · Gradient descent, vectors and embeddings, softmax and cross-entropy, and attention, each with a formula, a worked numeric example and a live version.ToolsSection · A truth-table generator with CNF, DNF and LaTeX output, a graph-traversal visualiser for BFS, DFS and Dijkstra, and a recursion-tree visualiser.LaTeXSection · How to format a CS conference or workshop paper in LaTeX, a camera-ready checklist, and a minimal template you can adapt.
About

About EntCS

EntCS is an independent educational site that explains computer science with interactive, step-by-step visualisations and free in-browser tools.

What the site is for

The site covers algorithms, discrete mathematics, the theory of computation and the mathematics behind machine learning, plus a small set of guides for writing computer-science papers in LaTeX. Each explainer pairs a careful written account with worked examples you can check by hand and an interactive version you can drive yourself. There are 21 pages at the moment, and more are planned, including the λ-calculus, type inference and automata constructions.

Independence

Independent educational site. Not affiliated with Elsevier, ENTCS or ENTICS.

The domain this site uses, entcs.org, was for many years the website of Electronic Notes in Theoretical Computer Science (ENTCS), a proceedings series published by Elsevier from 1995 until it was discontinued at the end of 2020. Its archive remains available on Elsevier’s ScienceDirect platform, and a successor series, ENTICS, now publishes in the same area.

Our name, EntCS, simply comes from the domain. It is not an abbreviation of that series and says nothing about it; the tagline, Explore. Visualise. Understand., is what the site is about.

EntCS has no connection with Elsevier, ENTCS, ENTICS or their editors. It does not host or reproduce any of the series’ papers, author instructions, macro packages or other files, and nothing on this site should be read as guidance from those organisations. Several pages keep their old addresses so that existing links still lead somewhere useful: /prelim.html is now our own guide to formatting a computer-science paper in LaTeX, and /final.html our own camera-ready checklist. Both were written from scratch for this site. Old addresses for style files and conference folders lead to the closest new guide; a handful of addresses that were abused by spammers years ago return “410 Gone”.

How pages are made

  • Accuracy first. Every worked example is computed by the same code that powers the interactive version, and the code is tested against known results: every sort really sorts, every DFA accepts exactly its language, and the softmax probabilities sum to 1.
  • Sources. Pages cite textbooks and original papers, with DOIs or arXiv links where they exist.
  • Our own work. The text, the visualisers and their design were written for this site.

Privacy

There are no accounts, no advertising and no tracking cookies. The tools run entirely in your browser: expressions, graphs, functions and numbers you enter are never sent anywhere. Two small preferences are stored only in your own browser’s local storage: your choice of light or dark theme, and the ticks on the LaTeX checklists. Clearing your browser’s site data removes them.

Accessibility

Pages work with a keyboard and a screen reader. Visualisers can be stepped with the arrow keys and the space bar, every step is described in text, and colour is never the only way information is shown. Animations respect your system’s reduced-motion setting. If something doesn’t work for you, that is a bug.