View source for Frobenius theorem on Pfaffian systems

A theorem on the conditions for a system of Pfaffian equations (cf. [[Pfaffian equation|Pfaffian equation]]) to be completely integrable, or (in geometrical terms) on conditions under which a given field of <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/f/f041/f041800/f0418001.png" />-dimensional tangent subspaces on a differentiable manifold is the tangent field of some [[Foliation|foliation]]. For several equivalent formulations of the Frobenius theorem, see the articles [[Involutive distribution|Involutive distribution]]; [[Cauchy problem|Cauchy problem]]; for a version with minimum differentiability requirements see [[#References|[2]]]. The name of the theorem is connected with the account of it in [[#References|[1]]], but does not accord with the information given there about its history.

====References====
<table><TR><TD valign="top">[1]</TD> <TD valign="top">  G. Frobenius,   "Ueber das Pfaffsche Problem"  ''J. Reine Angew. Math.'' , '''82'''  (1877)  pp. 230–315</TD></TR><TR><TD valign="top">[2]</TD> <TD valign="top">  P. Hartman,   "Ordinary differential equations" , Birkhäuser  (1982)</TD></TR></table>



====Comments====
G. Frobenius actually also treats the [[Normal form|normal form]] of a [[Differential form|differential form]] of degree 1.