Ferrers Diagram Calculator

Dot diagrams for partitions

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About Ferrers Diagram Calculator

A Ferrers diagram calculator drawing dot arrays for integer partitions. Each row has λ_i dots for part λ_i. Visualizes partition structure, conjugation (transpose), Durfee square, and hook lengths. Used in combinatorics and representation theory. Client-side.

Ferrers Diagram Calculator Features

  • Dot diagram
  • Conjugate overlay
  • Durfee square
  • Hook lengths
  • Interactive
Ferrers diagram: represent partition λ=(λ₁,λ₂,...,λ_k) as rows of dots. Row i has λ_i dots, left-aligned. Partition (4,2,1): ●●●● / ●● / ●. Transpose = conjugate. Young diagram = version with boxes instead of dots.

How to Use

Enter partition parts:

  • Diagram: Dot display
  • Conjugate: Transposed
  • Hooks: Hook lengths

Visual Insights

The Ferrers diagram instantly reveals: number of parts (rows), largest part (columns), conjugate (transpose), Durfee square (largest inscribed square), and self-conjugacy (symmetry about diagonal).

Hook Lengths

Hook at cell (i,j): h(i,j) = λ_i + λ'_j - i - j + 1. The hook length formula: f^λ = n!/Π h(i,j) counts standard Young tableaux. This is the Frame-Robinson-Thrall formula, fundamental in representation theory.

Step-by-Step Instructions

  1. 1Enter parts.
  2. 2View diagram.
  3. 3Toggle conjugate.
  4. 4See Durfee.
  5. 5Check hooks.

Ferrers Diagram Calculator — Frequently Asked Questions

What's the difference between Ferrers and Young diagrams?+

Ferrers uses dots: ●●●. Young uses boxes: □□□. Mathematically identical, but Young diagrams are preferred in representation theory because you can fill boxes with numbers (→ Young tableaux). Both represent the same partition.

How do diagrams show partition properties?+

At a glance: (1) Number of rows = number of parts. (2) Row lengths = part sizes in decreasing order. (3) Transpose = conjugate. (4) Symmetry = self-conjugate. (5) Fitting inside a rectangle = bounded partition.

What about skew partitions?+

If μ⊂λ (each part μ_i ≤ λ_i), the skew shape λ/μ is the Ferrers diagram of λ with μ removed from top-left. Skew shapes arise in Littlewood-Richardson rule, Schur function multiplication, and jeu de taquin.

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