Solution
= Solution
The sign map has abelian quotient, so $S_5'\leq A_5$. On the other hand $A_5'=A_5$ and $A_5\leq S_5$ imply $A_5\leq S_5'$. Hence
$$
\boxed{S_5'=A_5.}
$$
= Solution
The sign map has abelian quotient, so $S_5'\leq A_5$. On the other hand $A_5'=A_5$ and $A_5\leq S_5$ imply $A_5\leq S_5'$. Hence
$$
\boxed{S_5'=A_5.}
$$