Learn

Learning preferences

Make learning more comfortable. Changes apply immediately.

Enlarges page content, including diagrams and their labels. You can also use your browser’s zoom.

Choose the colours that are easiest for you to distinguish. Applies to lesson diagrams and lab plots. Labels, shapes, hatching and line patterns also distinguish meanings. Source photographs and raw image brightness stay unchanged; mask-only views are available for image overlays.

ExampleComparisonSample link

Saved in this browser on this device. Preferences are separate from progress backups.

Mathematics · unit version 1

Network incidence and the four spaces

Use oriented incidence matrices to connect conservation, cycles, potentials and orthogonal certificates. Signed real flows are allowed; capacities and nonnegative-flow constraints require additional models.

Open any lesson. Completion records participation; automatic practice checks and human judgment of written arguments are separate. This unit retains its own versioned requirements.

Readiness and preparation

Check your starting point

Try these short questions on paper, then compare your reasoning. They are optional self-checks, not a placement score or a navigation requirement. Use a targeted review when useful and return with your browser’s Back control.

For a matrix with six columns and rank four, how many independent kernel directions are there?

Network circulations live in edge coordinates, while conservation demands live in vertex coordinates.

Compare reasoning and find a refresher

Rank-nullity gives nullity six minus four, or two. The column count is the domain dimension; it must not be replaced by the number of vertex rows.

Review rank, kernels and pivot columns

Why does orthogonality certify a least-norm vector in an affine solution set?

The minimum-flow proof compares a feasible flow with every circulation, not just a few plotted alternatives.

Compare reasoning and find a refresher

If f is perpendicular to every allowed displacement z, then ||f+z|| squared equals ||f|| squared plus ||z|| squared. Every nonzero displacement increases the squared norm.

Review orthogonal projections and distance

Loading saved mathematics work…

Changed networks, energy and constraint audits

The mixed assessment has separate response history and review criteria; it does not change lesson participation records.

Lesson sequence

Each linked lesson opens on its own page. Expand its details here when you want to check the objectives before choosing.

  1. Read all four spaces of a network incidence matrix

    Lesson details and objectives

    Construct bases in vertex and edge coordinates, then prove how connected components and cycles determine the four spaces.

    • Construct all four fundamental spaces with their correct ambient coordinates for an oriented network.
    • Prove rank equals vertices minus connected components using a spanning forest over the real numbers.
    • Use component balances and cycle orthogonality to certify consistency and explain nonuniqueness.

    6 practice tasks.

  2. Conservation certificates and potentials

    Lesson details and objectives

    Use component balances to certify feasibility, then select a unique minimum-norm signed flow through vertex potentials.

    • Prove that component balance is the exact feasibility condition for signed incidence equations and exhibit left-null certificates of failure.
    • Derive the minimum-norm flow from orthogonality to circulations and the equation BBᵀp=b.
    • Separate potential gauge freedom and orientation conventions from edge-flow uniqueness and inequality constraints.

    8 practice tasks.