# guido giuliani

 Nov 12 awarded Tumbleweed Nov 5 asked Prove that $f$ is smooth if $x f$, $y f$ are smooth Aug 15 accepted Is this expression for the Riemann Tensor correct? Aug 15 comment Is this expression for the Riemann Tensor correct?The c's and the p's are smooth functions on the manifold Aug 15 asked Is this expression for the Riemann Tensor correct? Aug 15 accepted What does this notation means in noncommutative case Aug 14 comment What does this notation means in noncommutative caseBut in the page en.wikipedia.org/wiki/Covariant_derivative#Formal_definition they use the notation $V f$ also to indicate the directional derivative of a function along $V$. Then it is misleading to choose one or the other alternative above. How should I interprete? Aug 14 asked What does this notation means in noncommutative case Mar 2 awarded Yearling Mar 2 awarded Yearling Feb 4 accepted Find all the functions which satisfy a given functional equation Feb 2 revised Find all the functions which satisfy a given functional equationedited body Feb 2 comment Find all the functions which satisfy a given functional equation@DejanGovc I was editing while I received your post. Please check it again Feb 2 revised Find all the functions which satisfy a given functional equationadded 123 characters in body Feb 2 comment Find all the functions which satisfy a given functional equation@Alex did you assume $f(0)=0$ in your solution? Because then I'm pretty sure that $f(0)=-1$ is also possible. My apologies since I inverted $x,y$ in the first term of the equation. Please check the edited version. Still my apologies. BTW in this case setting $x=y=0$ gives $f(f(0))=f(0)^2+f(f(0))+f(0)$ from which $f(0)\in \{-1,0\}$. Feb 2 asked Find all the functions which satisfy a given functional equation Dec 5 asked Unusual Compact Embeddings Nov 13 asked solution of Lagrange differential equation are square integrable Nov 5 revised Ordering of two weak star limitsadded 492 characters in body Nov 5 comment Ordering of two weak star limitslol you are right...