I'm confused and probably have a thinking error. Exercise [6 on page 420](https://books.google.com/books?id=6iLUBwAAQBAJ&pg=PA420) of Lam's _Lectures on Modules and Rings_ says essentially: > Let $R$ be a ring and $C$ a cyclic right $R$-module: $C=R/A$ with some right ideal $A$ in R. Let $(-)^{*}$ denote the functor $Hom_R(-,R)$. Then $C^{*} \cong ann_l(A)$ as right R-modules. I would think that this is correct. Specialising to a $A=J$ being the Jacobson radical this gives: $C^{*} \cong ann_l(J) \cong soc(R)$ as the left annihilator of the Jacobson radical is the socle of the algebra (see [Lemma 8.3](https://books.google.sk/books?id=spmzW6-Pt-sC&pg=PA27) of Landrock's _Finite Group Algebras and Their Modules_). So Exercise 6 tells us that taking duals of simple modules gives again simple modules. In particular, the double dual of a simple module should again be the direct sum of simple modules?! Now take $R$ to be a local non-selfinjective algebra and $C=R/J$ (which is the unique right simple $R$-module). Let $S$ be the simple left $R$-module. Then we get $C^{*} \cong soc(R) \cong \oplus_{k=1}^{n}{S}$ for some $n$. Then we get doing the same again, $C^{**} \cong {\oplus}_{k=1}^{m}{C}$ for some $m$. But taking for example the algebra $R=K\langle x,y\rangle / (x^2,y^2,xy)$, my computer tells me that $C^{**}$ is not semisimple and has an indecomposable direct summand of dimension 2. I do not see the mistake at the moment, so maybe lemma 8.3. in the book of Landrock might be wrong?