I study the construction of derived Quot schemes in paper [“Shifted symplectic structures on derived Quot-stacks”][1].

Derived quot stacks are constructed from sheaves of non-positively graded dg algebras in section 3 of the paper.

In particular, I have some question about differentials of the dg algebras.

**Question**

1\) The last line of page 14, a differential is constructed by the morphism

$\mathcal{V}_j \otimes \left (\bigotimes_{1 \leq l \leq m+1} \mathcal{A}_{i_l} \right) \otimes (W_i)^\vee \rightarrow \mathcal{V}_j \otimes \left (\bigotimes_{1 \leq l \leq m} \mathcal{A}_{i_l} \right) \otimes (W_{i+i_{m+1}})^\vee$
 .

However it seems to me this morphism does not degree 0 morphism and this should be the morphism

$\mathcal{V}_j \otimes \left (\bigotimes_{1 \leq l \leq m+1} \mathcal{A}_{i_l} \right) \otimes (W_{i+i_{m+1}})^\vee \rightarrow \mathcal{V}_j \otimes \left (\bigotimes_{1 \leq l \leq m} \mathcal{A}_{i_l} \right) \otimes (W_{i})^\vee$
.

Is this correct ?

2\) Does the differential $\delta_W$ constructed from the above morphism really become a differential ? 
It seems to me that ${\delta_W}^2 \neq 0$

3\) Do we need the differential on $C^{\bullet}$ (not on $\mathcal{C}^{\bullet}$) constructed from the multiplication on $\oplus \mathcal{A_i}$ like that on $B^{\bullet}$ on line 10 of page 13. 


Thank you !


  [1]: https://arxiv.org/abs/1908.03021