Propositional Logic
Propositional Logic in Discrete Mathematics: implementation patterns, named pitfalls, and the autograder cases that catch them.
Computer Science Foundations
Propositional and first-order logic, induction and contradiction proofs, set theory and relations, combinatorial counting with inclusion-exclusion, graph theory through chromatic number, and number-theoretic algorithms. The hardest MIT 6.042 grading deduction is an induction proof that assumes the inductive hypothesis on the wrong variable, the structural error our tutors catch with explicit base-case plus inductive-step labeling. Verified CS graduates from Purdue, BITS Pilani, and Georgia Tech, starting at $20 per task, 12-hour average turnaround.
Why Discrete Mathematics
Propositional and first-order logic, induction and contradiction proofs, set theory and relations, combinatorial counting with inclusion-exclusion, graph theory through chromatic number, and number-theoretic algorithms. The hardest MIT 6.042 grading deduction is an induction proof that assumes the inductive hypothesis on the wrong variable, the structural error our tutors catch with explicit base-case plus inductive-step labeling. Verified CS graduates from Purdue, BITS Pilani, and Georgia Tech, starting at $20 per task, 12-hour average turnaround.
Topics covered
Propositional Logic in Discrete Mathematics: implementation patterns, named pitfalls, and the autograder cases that catch them.
Predicate Logic (First-Order) in Discrete Mathematics: implementation patterns, named pitfalls, and the autograder cases that catch them.
Truth Tables and Tautologies in Discrete Mathematics: implementation patterns, named pitfalls, and the autograder cases that catch them.
Natural Deduction (Fitch Style) in Discrete Mathematics: implementation patterns, named pitfalls, and the autograder cases that catch them.
Proof by Induction (Weak and Strong) in Discrete Mathematics: implementation patterns, named pitfalls, and the autograder cases that catch them.
Proof by Contradiction in Discrete Mathematics: implementation patterns, named pitfalls, and the autograder cases that catch them.
Full overview
Discrete mathematics is the mathematical foundation underneath every CS subject. Discrete math courses cover 8 named topic areas: propositional and predicate logic (truth tables, natural deduction, resolution, satisfiability), proof techniques (direct, contrapositive, contradiction, strong and weak induction, structural induction, well-ordering), set theory and relations (cardinality, Cantor diagonalization, equivalence relations, partial orders, lattices), functions and bijections (injection, surjection, pigeonhole, schroder-bernstein), combinatorics (permutations, combinations, binomial identities, inclusion-exclusion, generating functions), number theory (divisibility, gcd via Euclidean algorithm, modular arithmetic, Fermat little theorem, Chinese remainder theorem, RSA foundations), graph theory (paths, cycles, trees, planarity, Euler and Hamiltonian properties, chromatic number, matching theory, Ramsey theory), and formal language theory (regular languages and finite automata, context-free languages and pushdown automata, Turing machines and decidability, pumping lemmas, Chomsky hierarchy). MIT 6.042 (Mathematics for Computer Science), CMU 15-251 (Great Theoretical Ideas), Berkeley CS70 (Discrete Mathematics and Probability Theory), Stanford CS103 (Mathematical Foundations of Computing), and Princeton COS 240 each spend 13 to 15 weeks on these topics with Rosen, Lehman-Leighton-Meyer, or Epp as the textbook.
The assessment landscape is roughly 70-30 written problem sets over exams because proof-writing requires careful argument that is hard to grade in real time. MIT 6.042 problem sets are notorious for 8-hour completion times; CMU 15-251 grades both proof correctness and proof clarity (a correct proof badly written loses 30% of the credit). The required proof style is formal: every step justified, every quantifier bound, every base case verified.
CSHH tutor matching for this subject draws from CS graduates with mathematical maturity: former Putnam competitors, IMO medalists, math majors who minored in CS, plus theoretical CS PhDs comfortable with the standard textbook style. Our tutors deliver proofs in the canonical formats: 2-column for elementary geometry-style proofs, numbered-step format for induction, prose with displayed equations for analysis-style arguments, semantic tableaux or natural deduction trees for logic. Each proof comes with a 1-paragraph proof strategy memo explaining why the chosen technique fits the problem.
Languages supported: Lean 4 and Coq for formal proof verification on advanced assignments, Python and Haskell for combinatorial computation, Mathematica or SageMath for symbolic checking.
Where Students Get Stuck
Base case: verify the claim for the smallest n in scope (usually n equal to 0 or n equal to 1). Inductive hypothesis: assume the claim holds for some specific k (or for all k less than n in strong induction). Inductive step: prove the claim for k plus 1 (or n) using the hypothesis. We label each part explicitly and verify the induction variable is correct.
Negate forall by swapping to exists with negated predicate: not(forall-x P(x)) equals exists-x not(P(x)). Negate exists by swapping to forall with negated predicate. Compound quantifiers: not(forall-x exists-y P(x,y)) equals exists-x forall-y not(P(x,y)). We work through the negation step-by-step on the standard examples.
Two sets have the same cardinality if and only if there exists a bijection between them. Cantor diagonalization proves the reals are uncountable (no bijection from naturals to reals). Schroder-Bernstein theorem: if there exist injections A to B and B to A, there exists a bijection A to B. We construct explicit bijections for counting arguments and apply Cantor for uncountability proofs.
Count the union of n sets by alternating sums across all 2 to the n subsets: |A1 union A2 union ... An| equals sum |Ai| minus sum |Ai intersect Aj| plus sum |Ai intersect Aj intersect Ak| minus ... . The classic application: derangements (permutations with no fixed point). We track each term explicitly and verify on small cases (e.g., n equal to 3 gives 6 subsets).
Ordinary generating functions for sequences: f(x) equals sum a_n x to the n. Convert a recurrence (a_n equals a_{n-1} plus a_{n-2} for Fibonacci) to an algebraic equation in f(x), solve for f(x), then extract closed-form coefficients via partial fractions or power-series expansion. Exponential generating functions for labeled structures.
gcd(a, b) computed by Euclidean algorithm: gcd(a, b) equals gcd(b, a mod b) until b equals 0. Extended Euclidean computes integers x and y such that ax plus by equals gcd(a, b). We trace the algorithm on worked examples (gcd(252, 105) equals 21 with x and y derived by back-substitution) and use the Bezout coefficients for modular inverse.
Where It Appears
| Context | What we cover | |
|---|---|---|
| Mathematics for Computer Science (MIT 6.042, U of T CSC236, Manchester COMP11120, Edinburgh INFR08019, NUS CS1231S, IIT Bombay CS207) | Twelve problem sets covering proofs, induction, number theory, counting, probability, graphs, and recurrences. Problem sets are notorious for 6 to 10 hour completion times. Final exam includes a multi-part graph theory problem testing chromatic number bounds. | Discrete Mathematics implementations with tests |
| Great Theoretical Ideas (CMU 15-251, U of T CSC240, Manchester COMP11120, Edinburgh INFR08019, NUS CS3236, IIT Bombay CS207) | Covers proofs, counting, graphs, computability, complexity in a single course. Heavy emphasis on proof clarity: a correct proof badly written loses 30% of credit. Final project on a chosen theoretical topic with a 4-page paper. | Discrete Mathematics implementations with tests |
| Discrete Math and Probability Theory (Berkeley CS70, U of T CSC236, Manchester COMP11120, NUS CS1231S, IIT Bombay CS207, Sydney MATH1064) | Lehman-Leighton-Meyer textbook treatment. Problem sets on RSA cryptography (number theory application), error-correcting codes (linear algebra application), graph coloring (chromatic number bounds). Final exam includes RSA-decryption-by-hand problems. | Discrete Mathematics implementations with tests |
| Mathematical Foundations of Computing (Stanford CS103, U of T CSC236, Edinburgh INFR08019, NUS CS3236, IIT Bombay CS210) | Covers logic, sets, functions, regular languages, context-free languages, Turing machines, decidability, complexity. Heavy on formal language theory. Problem sets include explicit reductions between decidability problems. | Discrete Mathematics implementations with tests |
| Reasoning About Computation (Princeton COS 240, U of T CSC236, Manchester COMP11120, NUS CS1231S, IIT Bombay CS207) | Logic, induction, counting, graphs, computability in a discrete-math-meets-theory format. Problem sets include both proof problems and small-scale computational explorations (e.g., enumerate all 5-vertex graphs and check Eulerian property). | Discrete Mathematics implementations with tests |
| Generic Discrete Math (CS241 in the US, U of T CSC165, NUS CS1231, IIT Bombay CS207, Manchester COMP11120, Sydney MATH1064, used at 400+ universities) | Standard freshman or sophomore course covering Rosen textbook chapters 1 to 10. Common assignments: truth tables, proofs by induction on n equal to 0 base case, set theory with explicit Venn diagrams, combinatorial counting with permutations and combinations. | Discrete Mathematics implementations with tests |
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