<style>button,.story-clue{pointer-events:none}button{opacity:.55}.story-clue{pointer-events:auto}.panel-select{opacity:1}#app-status{display:none}</style>
A MATHEMATICAL ADVENTURE FOR CURIOUS MINDS

A small why. A big adventure.

Follow the story. Try a proof. Let curiosity choose how deep you go.

No account. No API key. Just curiosity.

Two ways in. One table between them.

I'd rather not fight math today

Walk in through the manga: seventeen chapters, sixty-four pocket pebbles, zero required formulas. The Lean source stays behind glass until you ask for it.

Straight to the mathematics

Begin at the proof map — thousands of named theorems — then climb the full ladder from clock inverses to R = T. The story keeps telling itself beside you; it will keep you honest.

Made for company: one reader who loves math and one who does not — one sofa. Whatever each of you finds carries over to the tea salon.

Start with “I don’t know yet.”

Seventeen chapters, one extraordinary argument. One small discovery is enough for today.

17 chapters · StoryOriginal source ↗

Pip’s rule: mistakes are clues. Every chapter is open, and every question allows another try.

Why the curve’s arithmetic cannot split the wrong way.

Choose your depthStart with the intuition.
Explore the whole proof29,511 theorems · original statements · dependencies

Search the local catalogue in English or Japanese. Major landmarks have Japanese titles. Open the full original proof on GitHub for the complete context.

Your discovery in this chapter

Name what modularity actually matches, and locate the deep theorem that supplies it.

Modularity
Here, an exact arithmetic match between a curve model and a suitable modular form.
Deep dependency
A separately proved result on which this chapter relies; a short call can hide a large proof.
Where the metaphor ends

The duet is a metaphor for exact arithmetic equalities. A modular form is not a sound wave, and the Frey curve does not literally sing.

</>Def_FLTPrelim_Modularity.lean
Original source ↗ · L93–102Pinned revision aa2d8b3
def IsModularModelOfLevel (W : WeierstrassCurve ℤ) (N : ℕ) : Prop :=
∃ f : CuspForm (CongruenceSubgroup.Gamma0 N) 2, f.IsNormalizedEigenform ∧
∀ p : ℕ, p.Prime → W.IsGoodPrimeFor p → ¬ p ∣ N →
ModularFormClass.qCoeff f p = (W.apOfModel p : ℂ)
def IsModularModel (W : WeierstrassCurve ℤ) : Prop :=
∃ N : ℕ, 0 < N ∧ W.IsModularModelOfLevel N
def IsModular (E : WeierstrassCurve ℚ) : Prop :=
∃ W : WeierstrassCurve ℤ, W.IsIntegralModelOf E ∧ W.IsModularModel

👩🏻‍🎨 Mika · Source reading guide

A curve gives a number at each suitable prime. A special function gives a sequence of numbers too. The job is to find a function whose numbers match the curve’s numbers. That exact partnership is called modularity. Read functions and coefficients first; the musical duet is a memory aid.

Annotated original · not a live Lean state

Point to a story clue or a highlighted term to connect the two.

Try this logical move →
Source and verification details

Source: anthropics/fermats-last-theorem @ aa2d8b3. Upstream reports verification; this reader has not independently rebuilt the project. Manga explanations are not formal proofs.

Source license & attribution
Chapter 8/17 · Story

The secret duet

Different instruments. The same arithmetic fingerprint.

How we got here

Keep the curve from the package in mind. We begin a second branch: modularity links arithmetic information from the curve with a modular form. The symmetry branch will meet this branch at level lowering.

These links explain the reading route. A story analogy is not a proof of this theorem.

Take it to the tea salon
PIP
“The curve gives us numbers. Finally, a fingerprint I can put in my notebook.”
Listen to the numbers

Story → proofThe device’s fingerprint is arithmetic data. The coefficients of the musical partner must match it at the specified primes.

Match the arithmetic scoreModularFormClass.qCoeff f p
PIP
“Then the numbers really match? My rehearsal budget was only one biscuit.”
The difficult bridge

Story → proofThe little bridge represents a correspondence at some positive level N. Its existence is a condition, not a guessed recipe.

The level is positive0 < N
MIKA
“Yes, at the primes specified by the definition. Finding that partner is the hard theorem.”
Credit where it is due

Story → proofConducting the duet connects the curve to its integral model. A separate modularity theorem supplies the actual partner.

Connect the two descriptionsW.IsIntegralModelOf E

The idea behind the story

A curve gives a number at each suitable prime. A special function gives a sequence of numbers too. The job is to find a function whose numbers match the curve’s numbers. That exact partnership is called modularity. Read functions and coefficients first; the musical duet is a memory aid.

Does the manga’s musical similarity establish modularity?

  • No. The exact arithmetic match requires a theorem.
  • Yes. The visual resemblance is the proof.

The story and source are readable here. Enable JavaScript to edit proofs, try quizzes, and explore the interactive map.

The matching form is sent to level two. Pip has booked a room that cannot hold it.

Read. Try. Make it click.

  1. Read the manga and choose Story, Math, or Lean depth.
  2. Open the proof playground. Edit the tactics and watch the goals change.
  3. Select a state, term, or hint. Wrong turns are part of the story.

The playground checks a small propositional language. FLT excerpts are editable reading material, not live-checked Lean proofs. The complete FLT build remains an upstream verification report.

I’m lost · Help

Mika’s help desk

The secret duet

One thing at a time

Start with the cake-scale story. You only need to read one small piece at a time. If you are in the Fermat story, start with Story depth, then the words listed before the chapter.

In simpler words

You do not need to know Lean, symbols or university mathematics to begin. Definitions come first in the small stories.

A small clue

Look at the small example before the general formula. Ask what changed and what stayed the same.

Close this panel to return to the exact place you were reading. These are prepared hints for this page.

Start with the first small story →