Chapter 1, page 7: In Definition 1.8, right before the exercise, the notation used is \$$a_1, a_2\$$ but becomes \$$a, b\$$ by the end of the sentence
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Chapter 1, page 9: Remark 1.16, the surjective function is showing a double headed arrow for the first time, maybe it's worth adding a notation footnote
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Chapter 1, page 9: Definition 1.19, missing period in "for any \$$x \\in X\$$ It is often"