Goldberg, Vladislav V.; Lychagin, Valentin V.; Akivis, Maks A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2004-03-31)
We find d − 2 relative differential invariants for a d-web, d ≥ 4, on a
two-dimensional manifold and prove that their vanishing is necessary and
sufficient for a d-web to be linearizable. If one writes the above invariants
in terms of web functions f(x, y) and g4(x, y), ..., gd(x, y), then necessary
and sufficient conditions for the linearizabilty of a d-web are two PDEs of
the fourth order ...