FUNCTION: uf_addvertex - add a vertex to a unit form

CALLING SEQUENCE:
uf_addvertex(q,c)

PARAMETERS:
q - matrix of the unit form
c - edges between the new vertex and other vertices defined as follows, c = [i₁,k₁,i₂,k₂,...], where |k_l | is the number of edges (solid if k_l<0, dotted if k_l>0) between vertices i_l and n+1.

SYNOPSIS:

• uf_addvertex adds a new vertex to the bigraph of a unit form.

EXAMPLES:

> q:=uf_init([1]);

> q:=uf_addvertex(q,[1,-1]);

> q:=uf_addvertex(q,[1,-1,2,1]);