Let $X,Y$ be independent random variables on the probability space $(\Omega,\mathcal{F},\mathbb{P})$ taking values in the measurable spaces $(E_1,\mathcal{E}_1),(E_2,\mathcal{E}_2)$. Consider a $\mathcal{E}_1\otimes\mathcal{E}_2$-measurable function $\phi:E_1\times E_2\to\mathbb{R}$ such that $\mathbb{E}[|\phi(X,Y)|]<\infty$ and for all $x\in E_1$ we have $\mathbb{E}[|\phi(x,Y)|]<\infty$.
How can I calculate $\mathbb{E}[\phi(X,Y)|\sigma(X)]$? Any ideas for me? Thanks.