**Credit Weight:** 0.5 **Prerequisite(s):** MHF4U or permission of the Chair of the Department **Description**: An introduction to proofs and to writing mathematics. Logic; propositional calculus; quantifiers, rules of inference, sets; set operations; cardinality and countability; relations, including partial orders and equivalence relations; functions; proof techniques such as direct proof; indirect proof; contradiction, and mathematical induction; basic properties of the integers. **Offering:** 0-0; 3-1 **Notes:** Students who have previous credit in Mathematics 1281 may not take Mathematics 1271/1272 for credit.