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Mathematics / A focused collection

Worked constructions

Walks, labelled graphs, polynomial obstructions, and compatible operators.

This collection brings together nine arguments that develop a construction from its constraints. The Mathematics directory includes all fourteen worked articles, starting points, and further notes.

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Matrices and graphs

  • A matrix identity by cycle exchange

    Cayley–Hamilton · 22 min

    Augment walks with reserved cycles, then pair terms with equal edge products and opposite signs to prove Cayley–Hamilton.

    Background: Matrix multiplication and the permutation definition of a determinant.

  • Classify compatible couplings

    14 min

    Multiply block matrices, derive the compatibility map and the allowed gauge map, then row-reduce.

    Background: Block matrices and solving linear equations over a field.

  • Construct every tensor chain

    18 min

    Build a lowering operator, solve its coefficient recurrence, and construct chains of every required length.

    Background: Finite-dimensional linear algebra and polynomial arithmetic; characteristic zero is explicit.

  • Cancel the unwanted edge sets

    12 min

    Choose the least available edge and pair terms by an involution that reverses their signs.

    Background: Finite graphs, subsets, and inclusion–exclusion.

Groups and labelled paths

  • Remove the tree, retain the circuits

    12 min

    Choose a root, propagate coordinate changes along a spanning tree, and read the remaining circuit products.

    Background: Graphs, multiplication and inverses in a group.

  • Calculate the missing components

    13 min

    Traverse the two-sided graph, retain both word labels, and calculate the intersection group attached to each component.

    Background: Finite groups, subgroups, left and right multiplication.

  • Split a cyclic tuple into motion and remainder

    12 min

    Separate the total sum from the remaining labels and calculate the face rules in those coordinates.

    Background: Tuples and addition in an abelian group; all operations are defined.

Polynomial equations and calculus

  • Make a hidden cubic appear

    11 min

    Change variables, eliminate a relation, and carry the residual through successive coefficients.

    Background: Polynomial expansion and coefficients of a power series.

  • Eliminate one integration variable

    13 min

    Integrate a selected edge parameter, then track the rational or logarithmic expression left behind.

    Background: One-variable integration and nonnegative improper integrals.

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