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šŸŽÆUnderstand Proof by Induction: The Domino Argument That Works

Build intuition for mathematical induction through the domino analogy and concrete number examples, then prove classic identities and write your own induction proof from scratch.

Foundations14 drops~2-week path Ā· 5–8 min/daymath

Phase 1The Domino Setup

See why the domino argument actually works

4 drops
  1. Knock one domino down and trust the chain

    6 min

    Knock one domino down and trust the chain

  2. Skip the base case and you can prove anything

    7 min

    Skip the base case and you can prove anything

  3. Assume it works, then prove it still works one step later

    7 min

    Assume it works, then prove it still works one step later

  4. Three ways to write a proof that proves nothing

    7 min

    Three ways to write a proof that proves nothing

Phase 2Proving Classic Identities

Prove classic identities step by step

5 drops
  1. Stack squares into a pyramid and count the blocks

    7 min

    Stack squares into a pyramid and count the blocks

  2. Multiply by r and watch terms cancel like magic

    6 min

    Multiply by r and watch terms cancel like magic

  3. Proving that 2ⁿ grows faster than n² — and when it starts

    7 min

    Proving that 2ⁿ grows faster than n² — and when it starts

  4. Prove that n³ āˆ’ n is always divisible by 6

    7 min

    Prove that n³ āˆ’ n is always divisible by 6

  5. Pin down Fibonacci growth with a two-step induction

    8 min

    Pin down Fibonacci growth with a two-step induction

Phase 3Induction in the Wild

Compare weak, strong, and structural induction

4 drops
  1. When one predecessor isn't enough

    7 min

    When one predecessor isn't enough

  2. Trees aren't numbers — but induction still works on them

    7 min

    Trees aren't numbers — but induction still works on them

  3. Spot the bug before it infects the theorem

    7 min

    Spot the bug before it infects the theorem

  4. Weak, strong, or structural — pick the right induction

    7 min

    Weak, strong, or structural — pick the right induction

Phase 4Your Own Proof

State and prove your own induction claim

1 drop
  1. State a claim, build the dominoes, push the first one

    8 min

    State a claim, build the dominoes, push the first one

Frequently asked questions

Why is the base case necessary?
This is covered in the ā€œUnderstand Proof by Induction: The Domino Argument That Worksā€ learning path. Start with daily 5-minute micro-lessons that build from fundamentals to hands-on application.
What is the difference between weak and strong induction?
This is covered in the ā€œUnderstand Proof by Induction: The Domino Argument That Worksā€ learning path. Start with daily 5-minute micro-lessons that build from fundamentals to hands-on application.
Can induction prove something false if the base case is wrong?
This is covered in the ā€œUnderstand Proof by Induction: The Domino Argument That Worksā€ learning path. Start with daily 5-minute micro-lessons that build from fundamentals to hands-on application.
When should I use structural induction?
This is covered in the ā€œUnderstand Proof by Induction: The Domino Argument That Worksā€ learning path. Start with daily 5-minute micro-lessons that build from fundamentals to hands-on application.