Discrete Mathematics: Why Seven Bridges Started a Science
Logic, proof, counting, recurrences, graphs, modular arithmetic and probability: the math of separate things that underpins all of computing.
Discrete Mathematics · 50 questions
Try 3 questions
1. If the statement 'all ravens are black' is false, what must be true?
- Every raven is another color
- No raven at all is black
- At least one raven isn't black
Show the answer
Answer: At least one raven isn't black
The negation of 'all are' is 'at least one is not'; a single white raven is enough to make the claim false.
2. Which statement is logically equivalent to 'If it is a square, then it is a rectangle'?
- If not a square, then not a rectangle
- If a rectangle, then it is a square
- If not a rectangle, then not a square
Show the answer
Answer: If not a rectangle, then not a square
The contrapositive always has the same truth value; the converse and the inverse do not.
3. Is 'every unicorn in this room is purple' true when the room contains no unicorns?
- Yes, it is vacuously true
- No, it is simply false
- It has no truth value
Show the answer
Answer: Yes, it is vacuously true
A universal claim is false only if a counterexample exists; with no unicorns there is none, so it is true by default.
The whole quiz comes before your apps
BrainTok asks a few questions like these before the apps you choose open, so your screen time turns into learning. For iPhone.
Join the beta