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Aug 9, 2022 at 15:27 comment added LSpice I think that this answers "does $S_n$ embed in $A_{n + 1}$ for all $n \ge 2$?" (in the negative), but it fails to prove "$S_n$ does not embed in $A_{n + 1}$ for all $n \ge 2$", of which the usual parenthesisation is "($S_n$ does not embed in $A_{n + 1}$) for all $n \ge 2$".
Aug 9, 2022 at 13:48 comment added Alex M. Not quite: the problem could have easily been restated for $n \ge 3$. The point here is not to solve a problem, but to understand the deep reason for which a mathematical fact is true, which your solution does not do. In other words, your solution chooses to go for the "low-hanging fruit".
Aug 9, 2022 at 13:37 comment added Dario Sure, in Rotman's exercise the question was posed for $n\geq 2$, so the counterexample with $n=2$ was sufficient.
Aug 9, 2022 at 12:20 review Late answers
Aug 9, 2022 at 12:41
Aug 9, 2022 at 12:15 comment added Alex M. The problem is that you only attempt to prove that $S_2$ cannot be embedded in $A_3$, but maybe the embedding is true for $n \ge 3$.
S Aug 9, 2022 at 12:02 review First answers
Aug 9, 2022 at 12:15
S Aug 9, 2022 at 12:02 history answered Dario CC BY-SA 4.0