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Prescribed-area square word core

Abstract

Literal expansion, ordered base-eight source blocks and exact-area square words with a common joint moment image.

Definition 1.1 (Level-three Boolean indices).

Lean statement: D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.level3Index

Formalization. D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.level3Index (✓ std3).

Source. Repository-derived.

Commentary.

The index is the function with values x,y,z on Fin 3. True denotes a and false denotes b.

Definition 1.2 (The first P source).

Lean statement: D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.P0

Formalization. D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.P0 (✓ std3).

Source. Repository-derived.

Commentary.

P0 is the positivePairWords second component at index (true,false,true), the literal baaab.

Definition 1.3 (The second P source).

Lean statement: D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.P1

Formalization. D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.P1 (✓ std3).

Source. Repository-derived.

Commentary.

P1 is the first component at that same index, the literal ababa.

Definition 1.4 (The first Q source).

Lean statement: D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.Q0

Formalization. D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.Q0 (✓ std3).

Source. Repository-derived.

Commentary.

Q0 is the second component at index (true,false,false), the literal babab.

Definition 1.5 (The second Q source).

Lean statement: D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.Q1

Formalization. D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.Q1 (✓ std3).

Source. Repository-derived.

Commentary.

Q1 is the first component at that same index, the literal abbba.

Definition 1.6 (The four selected blocks).

Lean statement: D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.H

Formalization. D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.H (✓ std3).

Source. Repository-derived.

Commentary.

H(e,f) is P_e followed by Q_f,Q0,P0. Its counts are (10,10), its scattered ab area is 50, and its G coordinates are (10,10,0,−92−24e−12f,−136−12e−24f), with Boolean values represented by zero or one.

Theorem 1.7 (Rows of the actual repeated word).

Proof. Machine-checked in Lean as D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.rows_literalPowerWord (✓ std3). ∎

Source. Repository-derived.

Commentary.

Each actual row is repeated n times and multiplied by n. The identity includes n=0 and the empty word.

Theorem 1.8 (Homogeneity of the actual fan).

Proof. Machine-checked in Lean as D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.G_literalPowerWord (✓ std3). ∎

Source. Repository-derived.

Commentary.

The row identity scales area quadratically and both the square-row and odd-row sums cubically. The existing actual fan formulas then give all five homogeneous coordinates.

Definition 1.9 (Dyadic radix).

Lean statement: D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.q

Formalization. D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.q (✓ std3).

Source. Repository-derived.

Commentary.

q(J)=2^J.

Definition 1.10 (Core side).

Lean statement: D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.coreSide

Formalization. D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.coreSide (✓ std3).

Source. Repository-derived.

Commentary.

coreSide(J)=70(q(J)−1), an even natural number.

Definition 1.11 (The full core index domain).

Lean statement: D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.CoreIndex

Formalization. D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.CoreIndex (✓ std3).

Source. Repository-derived.

Commentary.

CoreIndex(J)=Fin(q(J)^3) × Fin(q(J)^3).

Definition 1.12 (The actual ordered core).

Lean statement: D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.V

Formalization. D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.V (✓ std3).

Source. Repository-derived.

Commentary.

Use Nat.digitsAppend 8 J for both coordinates. In increasing scale i, concatenate the seven thresholds ℓ=1,…,7 of H(ℓ≤d_i,ℓ≤e_i), with each letter repeated 2^i times. For J=0 this is an auxiliary empty word contribution; it is not a native empty tree.

Definition 1.13 (The exact quotient/remainder suffix).

Lean statement: D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.fixedZ

Formalization. D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.fixedZ (✓ std3).

Source. Repository-derived.

Commentary.

For b>0 and 0≤κ≤b², let j=κ/b and z=κ mod b. At z=0 use b^(b−j)a^b b^j; otherwise use b^(b−j−1)a^z b a^(b−z)b^j. Its direct rows are j copies of b, followed when z>0 by z, followed by the required zero padding. The exponent guards include κ=0 and κ=b².

Definition 1.14 (Suffix area).

Lean statement: D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.suffixArea

Formalization. D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.suffixArea (✓ std3).

Source. Repository-derived.

Commentary.

suffixArea(J,h,t)=t+coreSide(J)²/2−coreSide(J)h in natural arithmetic. The square hypotheses prove nontruncation and the upper bound (h−coreSide(J))² before this subtraction is used.

Definition 1.15 (The completed square word).

Lean statement: D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.W

Formalization. D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.W (✓ std3).

Source. Repository-derived.

Commentary.

W(J,h,t,x)=V(J,x) followed by fixedZ(h−coreSide(J),suffixArea(J,h,t)). The suffix is fixed across the full core index domain.

Theorem 1.16 (Exact area and simultaneous joint injection).

Proof. Machine-checked in Lean as D5/S3/Combinatorics/Partitions/PrescribedAreaSquareWordCore.square_family (✓ std3). ∎

Source. Repository-derived.

Commentary.

For every natural J,h,t with h>0, 8a≤h and h²≤8t≤7h², the actual words have counts (h,h), area exactly t and h sorted direct rows bounded by h. Membership in wordFiber includes nonemptiness. The core has zero D, while the completed square has D=2t−h². Concatenation translates the suffix rows by a and adds the fixed moment vector (E_Z+3aD_Z,F_Z+3aD_Z). For μ=rows(W), the direct fan formulas give E=h³−6ht+6 squareRows(μ) and F=−h³+6ht−6 oddRows(μ); the latter statistic is the square-column sum of the same Ferrers diagram. The independent core directions (−24,−12) and (−12,−24) have determinant 432. Consequently the same actual word supplies both moments, and its squareRows and oddRows pair is also injective. Each of the word, joint fan and joint row-statistic images has exactly q^6 elements, giving that lower bound in the existing whole word-fiber capacity. J=0 is included. The direct area t is preserved even above h²/2, without reversing the core.

References