# All Questions

316 views

### Finding the general solution of a quasilinear PDE

This is a homework that I'm having a bit of trouble with: Find a general solution of: $(x^2+3y^2+3u^2)u_x-2xyuu_y+2xu=0~.$ Of course this should be done using the method of characteristics but I'm ...
159 views

### What are 'weak' forms of Urysohn's lemma, which do not require choice?

Reference: http://web.mat.bham.ac.uk/C.Good/research/pdfs/horror.pdf It is well known that the original proof of Urysohn's lemma uses a choice principle. (DC) What are weak forms of the Urysohn's ...