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Mathematics · unit version 1

Discrete synthesis: schedules, sampling and certificates

Connect precedence proofs, combinatorial sample spaces and dependent indicators. Use targeted returns to matching, orders, planarity and modular arithmetic without requiring whole advanced courses.

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Readiness and preparation

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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.

Does a topological ordering give an optimal parallel schedule?

Feasibility, elapsed time and worker constraints are different claims.

Compare reasoning and find a refresher

It orders prerequisites before dependents. Optimal elapsed time additionally needs durations and a resource model; unlimited-worker earliest finishes need not form a feasible schedule with a worker limit.

Review precedence and source removal

Must random quantities be independent to add their expectations?

Sampling without replacement commonly creates dependence.

Compare reasoning and find a refresher

No. For finite random quantities, expanding the finite weighted sums proves E[X+Y]=E[X]+E[Y]. Independence is needed for a general product factorization, not this sum rule.

Review indicators and finite expectation

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Changed constraints and random precedence

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Lesson sequence

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  1. Weighted precedence and scheduling

    Lesson details and objectives

    Build earliest schedules, prove their optimality and diagnose the resource assumptions behind the proof.

    • Derive earliest finish times from a dependency DAG and construct a feasible parallel schedule.
    • Prove the recurrence using a processed-prefix invariant and an independent path lower bound.
    • Repair or delimit the model when durations, release times, worker counts or cycle assumptions change.

    8 practice tasks.

  2. Count dependent events and prove a tail bound

    Lesson details and objectives

    Build a finite probability model, add indicator expectations without independence, and sharpen a tail bound using pairs of events.

    • Derive a finite sample space and indicator expectations from the actual sampling mechanism.
    • Test dependence using joint and conditional probabilities rather than shared vocabulary.
    • Prove first-moment and factorial-moment tail bounds pointwise and identify when equality holds.

    6 practice tasks.