Math 221: Discrete Mathematics, Spring 2025
Professor: Darij Grinberg
Organization
Course description
This course introduces a range of topics in Discrete Mathematics, including set theory, counting, number theory,
combinatorial games, and cryptography.
Level: undergraduate.
Prerequisites: Math 220 (Introduction to Proofs) or CS 270 (Mathematical Foundations of Computer Science) or ECE 200 (Digital Logic Design).
Course materials
- Required:
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- Recommended:
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- Remedial:
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Course calendar
- Writing:
- Diary:
- Homework:
- Everything from this point on is tentative and subject to change (including the problems and the deadlines).
- No Copyright:
- The above lecture notes and assignments have been released under the CC0 license, i.e., are dedicated to the public domain. They can be copied, modified and distributed without permission. See the license for details.
Grading and policies
- Grading matrix:
- 40%: homework sets. (Your lowest homework score will be dropped.)
- 20%: midterm 1.
- 20%: midterm 2.
- 20%: midterm 3 (due in finals week).
- Grade scale:
- These numbers are tentative and subject to change:
- A+, A, A-: (80%, 100%].
- B+, B, B-: (60%, 80%].
- C+, C, C-: (40%, 60%].
- D+, D, D-: (20%, 40%].
- Homework policy:
- Collaboration and reading is allowed. However, each of you must write his solutions independently (in his own words) and acknowledge all sources used.
- Asking outsiders (anyone apart from Math 221 students and Drexel employees) for help with the problems is not allowed. (In particular, you cannot post homework as questions on math.stackexchange before the due date!)
- The use of generative AI (ChatGPT, Bard, etc.) in solving problems or formulating the solutions is not allowed. However, it is permitted to consult AI for typesetting and formatting questions.
- Late homework will not be accepted. (But keep in mind that the lowest homework score will be dropped.)
- Solutions have to be submitted electronically via Gradescope. Solutions must be typeset; handwriting will not be accepted! To typeset text with formulas, you can use any of LaTeX (a free online editor is Overleaf), Markdown (a free online editor is Stackedit), LibreOffice (which has a built-in equation editor), Google Docs (which, too, has an equation editor inside), or many other tools. You can even type in a text editor if you use standard conventions to write your formulas in ASCII. In either case, convert to PDF (e.g., by printing to PDF) and submit to Gradescope.
If there are problems with submission, send your work to me by email for good measure.
- Midterm policy:
- Late midterms will not be accepted unless agreed in advance and with serious justification.
- Collaboration is not allowed on midterms.
- Everything else is the same as for homework (yes, midterms are take-home).
- Expected outcomes:
- The students should have gained experience and familiarity with the mainstays of discrete mathematics: the language of sets and maps; proofs by induction; basic principles of enumeration; integers and their divisibility properties; prime numbers and possibly their use in cryptography.
Other resources
- University policies:
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- Disability resources:
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