SEMIDEUS
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The learning app that proves understanding

Understand for real.Think for yourself.

Master the concepts you study, with proof you truly understand them. Question them, connect them, defend them. Become a mind that thinks, not one that waits for answers.

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Explain it · KV cacheExample
“It stores the keys and values from earlier tokens, so the model doesn't recompute them for every new token.”
Verdict
Accurate and clear.
Missing
What it costs. Memory grows with every token in the context.
Next question
So what happens to that memory when the conversation doubles in length?

The illusion of knowing

You've read it. Do you really understand it?

You read the paper. You asked the AI to walk you through it. You saved the best parts and it all made sense. Then someone asks a question you didn't expect, and you realize the AI did the thinking.

Psychologists call the first part the illusion of explanatory depth: we feel we understand things better than we can explain them. AI widens it, because letting it think for you feels exactly like learning.

  • Hours of reading that don't add up.
  • The meeting where you can't defend the decision.
  • Reaching for the AI before you've thought it through.

What you have

  • Saved papers
  • AI summaries
  • Highlights
  • A course certificate

Feels like knowing

What you can do

  • Explain it in your own words
  • Reason about it when questioned
  • Still know it next month

Is knowing

The research

Understand for real

Find out what you really understand.

Pick one idea from what you're learning. Explain it in your own words and get an honest verdict, with what you missed.

  1. 01

    Bring

    A paper, a PDF, an article or a talk. Semideus turns it into cards, questions and a map of the ideas.

  2. 02

    Explain

    Say it in your own words, typed or spoken, or teach it to Daimon, our teachable AI.

  3. 03

    Verdict

    Graded on accuracy, depth, clarity and your own examples. The gaps are named.

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Then it comes back before it fades, until you've proven it twice, days apart.

Think for yourself

An AI that asks, so you do the thinking.

Most AI hands you the answer. Here it asks the questions: why, what if, what would break. You answer, it pushes back, and you find out whether your reasoning holds.

  • Reason under questioningHold your own when someone pushes back.
  • Know what you knowSee where your understanding is solid and where it isn't, idea by idea.
  • Think before you askOn every proof the guide goes quiet, so the thinking stays yours.
Socratic tutor · KV cacheExample

  1. Tutor

    You said the cache saves work. What does it cost you?

  2. You

    Memory. It grows with every token.

  3. Tutor

    Then what would you change if the context had to double?

Reasoning heldThe tutor never gives you the answer.

What changes

From borrowed answers to a mind of your own.

  1. Forming

    Your first session

    You find out what you really understand.

    • Explain an idea from your own material and see what's missing.
  2. Proven

    The weeks after

    What you learn becomes yours.

    • Review only what's fading, in a few minutes a day.
    • Always know the one next thing to study.
    • Finish ideas: each one closes when you show you understand it.
  3. Sealed

    Over months

    You become a mind that thinks for itself.

    • Hold your own when someone pushes back.
    • Know where you stand on every idea.
    • Keep a record of what you've mastered that anyone can verify.

No streaks. No points. Only what you can show.

No mark-as-learned button

Built so you can't fool yourself.

An idea is finished only when you show you understand it, and it's sealed only when you prove it again at least three days later. Flashcards keep memory alive, but they can never finish or seal an idea.

Some checks use no AI at all: you rebuild how ideas connect, and it's compared against your own map.

  • Graded on published rubrics: accuracy, depth, clarity and your own examples. How we grade
  • Other users never see your material, and records stay private until you share one.
  • Retrieval practice and spacing are among the best-supported ways to learn. The evidence

Proof of understanding

KV Cache

Understanding proven twice, days apart.

First proven
7 Aug 2026
Re-proven
10 Aug 2026

At least 72 hours apart, enforced by the database.

Signed. Anyone can verify it.

What it attests, and what it does not

Two graded understanding performances, days apart. Not attested: identity beyond the name given, closed-book conditions, or that the memory will last.

See the real record

How it works

Four steps. Every one is practice.

  1. 01

    Bring what you're learning.

    PDFs, papers, articles, YouTube and notes, or straight from Claude. Semideus turns it into cards, questions and a map of the ideas.

  2. 02

    Explain it, or be questioned on it.

    Type it, say it, teach it to Daimon, or face a tutor that only asks questions.

  3. 03

    See what you missed.

    You're graded and the gaps are named, so you know what to fix.

  4. 04

    Prove it again, days later.

    Review brings ideas back before they fade. Prove one twice, three days apart, and it's sealed.

The test is the training. Explaining an idea, or defending it, is how you learn it, not only how you check it.

Under the hood
  • Review is scheduled with FSRS, the open algorithm also used in Anki.
  • Ideas move from forming to proven as graded evidence builds up.
  • A loop only closes when you show you understand the idea, and a record is only sealed after a second proof at least three days later.
  • Explanations are graded by Claude against fixed rubrics.
  • Rebuilding an idea's connections is checked by direct comparison, with no model involved.
  • Records are signed with Ed25519, and anyone can verify one.

Pricing

Start free. Go further when you're ready.

Free

€0/month

Bring what you're learning and start mastering it.

  • Bring your sources and build cards, tests and a map of ideas
  • Spaced review
  • Teach Daimon and see what it still gets wrong
  • Take a position and defend it
  • Rebuild ideas from memory
  • 400 credits to start
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Pro

€14.99/month

Graded explanations and a tutor that questions your reasoning.

  • Everything in Free
  • Graded explanations, typed or spoken
  • The Socratic tutor that questions your reasoning
  • Connect Claude to your material
  • Your balance refills to 4,000 credits every month
Choose Pro

Credits pay for AI work such as building cards and grading. Review never costs credits. Top up anytime with a credit pack.

Questions

Can AI really judge my understanding?

It grades against fixed rubrics and names specific gaps you can check yourself. Some checks use no AI at all. It isn't a proctored exam, and every record says so.

Why not ask ChatGPT or Claude to quiz me?

That chat never ends, keeps no record of what you've proven, and the answer is one message away. Here the AI asks and you answer, every session ends with a verdict, and what you prove comes back before it fades. You can connect Claude to your Semideus material too.

Will it make me a better thinker?

We don't promise a better brain. Semideus makes you do the thinking: explain, get questioned, defend your view, and prove it again days later. What we measure is what you understand.

Isn't this just flashcards?

Flashcards keep memory alive. They can never finish an idea here. Only showing that you understand it can.

How much time does it take?

Sessions are short and they end. Review only shows what's due.

What's free?

Bringing sources, cards and maps, spaced review, teaching Daimon, taking a position and defending it, and rebuilding ideas from memory. Pro adds graded explanations, the Socratic tutor and the Claude connection.

Start now

Pick one idea. Find out if you really understand it.

The answers are free now. The thinking is still yours.

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Free plan. No card needed.