id	author	title	date	pages	extension	mime	words	sentence	flesch	summary	cache	txt
ap-1805	Himmel, Martin	On the Solvability of Some Partial Differential Inequality	2013	6	.pdf	application/pdf	4808	288	67	Thus, it is possible to interpret integrating factors and Dulac functions as invariant functions to certain cofactors: an inte- grating factor is nothing but an invariant function having cofactor k = −divX (16) and a Dulac function is an invariant function with cofactor k = − divX + 1 f · g, (17) The multiplier B ∈W 1,p(Ω,R) is called Dulac function of the planar dynamical system (1) in Ω ⊆ D if and only if there is a real-valued continuous function g > 0 having a positive sign in Ω except on a set of Lebesgue measure zero such that the equation div(BX)	cache/ap-1805.pdf	txt/ap-1805.txt