# Daan Michiels

Belgium

 Nov 21 awarded Supporter Nov 13 awarded Supporter Nov 12 awarded Supporter Oct 28 awarded Self-Learner Aug 6 awarded Yearling May 29 comment What is the accepted notation for natural logarithms, trig functions and powers?@J.M. - Observation about the arc: in Dutch, the inverse trig functions have names starting with boog, which means arc (a piece of a circle). I don't know why. Wikipedia has a paragraph on the etymology of arc. en.wikipedia.org/wiki/… May 22 accepted Every principal $G$-bundle over a surface is trivial if $G$ is compact and simply connected: reference? May 16 comment Every principal $G$-bundle over a surface is trivial if $G$ is compact and simply connected: reference?Thanks for the answer. Any reference I can take a look at? May 15 answered Deduce dice configuration knowing 2 adjacent faces May 14 comment The number of words that can be made by permuting the letters of _MATHEMATICS_ isExample: the number of words that can be made by permuting the letters of BEER is 12. The possibilities are EEBR, EERB, EBER, EREB, EBRE, ERBE, BERE, REBE, BREE, RBEE, BEER, REEB. May 14 awarded Caucus Apr 25 comment Every principal $G$-bundle over a surface is trivial if $G$ is compact and simply connected: reference?@EricO.Korman - Thank you, that helps (though I have to think about it a little bit). Apr 23 comment Every principal $G$-bundle over a surface is trivial if $G$ is compact and simply connected: reference?I am familiar with the fundamental group and with singular and de Rham (co)homology. I can define the higher homotopy groups, but I cannot state any relevant "big theorems" by heart. I think I know what classifying spaces are about, meaning that in particular I more or less know the correspondence between homotopy classes of maps $\Sigma\to BG$ and $G$-bundles over $\Sigma$. I have never really worked with higher homotopy groups. (And I'm aware it may be hard to give a good answer to someone lacking this knowledge.) Apr 23 asked Every principal $G$-bundle over a surface is trivial if $G$ is compact and simply connected: reference? Apr 13 comment How to classify principal bundles over a 2 dimensional surface?@HenryT.Horton - If $M$ is 2-dimensional and $N$ is 2-connected, why is $[M,N]=0$? (I'm new to homotopy theory.) Mar 24 awarded Revival Mar 22 awarded Nice Question Mar 22 accepted Characterizing singularities using sheaves of smooth functions Mar 21 answered Is there a better measure of variation for fractional numbers than standard deviation? Mar 20 comment Topology of finite complementsHint: if singletons are closed, then so are finite sets.