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3 cards from this section. Quick, good the night before a test.
Define an injective function.
Think about how inputs are related to outputs.
What is the range of this function: f: {1, 2, 3} → {a, b} where f(1)=a, f(2)=b, f(3)=b?
Look for the outputs produced from the inputs.
What is an injective function?
Focus on the uniqueness of mapping.
Is a function f: {1, 2} → {a, b} with f(1)=a and f(2)=b both injective and surjective?
Check both properties for verification.
Given two sets A = {1, 2, 3} and B = {a, b, c, d}, can we have a surjective function defined from A to B? Justify your answer.
Think about the number of outputs compared to inputs.
Construct an example of a function f: {1, 2, 3} → {x, y} that is injective but not surjective. Explain your choice.
Make sure to check for any repeated outputs when creating your function.
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