Discrete Mathematics for CS 7 units 44 lecture hours

Maths Study Guide

A plain-language walkthrough of the whole syllabus. Every idea is explained simply, drawn out with a diagram, and paired with a memory trick so it sticks.

How to use this guide

Work through one unit per sitting. Read the idea, look at the picture, copy the trick into your notebook, then try the worked example with the page covered. Each unit ends with a 3-question self-check.

The 7 units at a glance

The syllabus is really just four big chapters. Notice how they build on each other:

SETS & LOGIC COUNTING & PROBABILITY STATISTICS GRAPHS U1 Relations & Functions U2 Permutations U3 Probability, Bayes U4 Distributions U5 Significance Testing U4 Normal & Binomial U5 Hypothesis Tests U6 Graphs U7 Trees 6 hrs 26 hrs (inside U4/U5) 12 hrs
Units 3, 4 and 5 are one continuous story: probability → distributions → testing. Learn them in that order or you will drown.
UnitTopicCLOLecture hrsWeightCore idea in one line
1Functions & Relation16~11%Sets and the rules that connect them
2Counting, P & C14~9%Counting without actually counting
3Probability26~14%How likely is something?
4Distributions36~14%Probability given as a formula
5Significance Testing310~23%Deciding if a result is real or noise
6Graph Theory46~14%Networks of points and links
7Trees46~14%Hierarchies and cheapest networks
Heads up

Unit 5 (Significance Testing) has the most lecture hours — 10 of 44. It is the single most exam-heavy topic. Give it the most revision time.

A 7-day revision plan

Days 1–2 · The maths core

Unit 1 (relations, function types, recursion) and Unit 2 (counting, P & C). Unit 2 is short but appears inside other units' questions.

Days 3–4 · The probability block

Unit 3, then Unit 4, then Unit 5 in that order. Do not jump to Unit 5 — every hypothesis test is built on the distributions from Unit 4.

Day 5 · Graphs

Unit 6: terminology, degree, adjacency/incidence matrices, Dijkstra, colouring.

Days 6–7 · Trees & mixed practice

Unit 7 (traversal, spanning trees, Kruskal/Prim), then mixed past-paper questions to catch weak spots.

Five ideas that unlock the whole syllabus

Almost every question you meet is one of these five ideas wearing a different hat.

COUNT EVERYTHING How many ways? P&C, pigeonhole (U2) How likely? Probability, Bayes (U3) What shape is the data? Normal, binomial, tests (U4–5) How connected? Graphs, paths, trees (U6–7) …and Unit 1 defines the language all of it is written in.
If you can count, you can do probability; if you can do probability, you can do statistics; graphs are their own world.
Master trick

"Without order" vs "with order". Almost the entire syllabus reduces to this one question.

  • Order matters → nP r = n!/(n−r)! → Dijkstra, trees, functions
  • Order does not matter → nC r = n!/[r!(n−r)!] → combinations, binomial coefficients

When an exam question looks hard, ask: "is this about order, or not?"

How to attack an exam question

  1. Name the unit. Counting objects? P&C. Chance? Probability. "Is it significant?" Unit 5. Network? Graph/tree.
  2. Find the trigger word. at least one, no two, all, exactly, round, first, cheapest, at most — each one flips the formula. The tricks page lists them all.
  3. Check the domain. In Unit 1 most errors come from using the wrong set. Draw the Venn diagram first.
  4. Write one line of justification. Almost every mark in this syllabus is for a reason, not just a number.
  5. Sanity-check. Probability must land between 0 and 1. Counts must be whole numbers. Degrees of an undirected graph must sum to an even number.
Most common mistakes
  1. Using nC r when order matters (or the reverse).
  2. Adding probabilities for independent events instead of multiplying.
  3. Forgetting to apply the continuity correction in the normal approximation.
  4. Confusing "accept" with "fail to reject" the null hypothesis.
  5. Not converting a one-tailed test to two-tail by doubling the critical area.
  6. In graphs: forgetting a graph with n vertices needs at least n−1 edges to be connected.

Jump straight to a unit

01 · Relations & Functions

Cartesian products, the four relation types, floor/ceiling, boolean, recursion.

02 · Counting, P & C

Basic principle, pigeonhole, nPr, nCr, Pascal's triangle.

03 · Probability & Bayes

A+B, A·B, exclusive vs independent, conditional, Bayes.

04 · Distributions

Normal curve, binomial, normal approximation to binomial.

05 · Significance Testing

H0 vs H1, critical values, one/two-tailed, z & t tests.

06 · Graph Theory

Degree, handshaking, adjacency/incidence matrix, Dijkstra, colouring.