E. Arrondo, APPENDIX TO CONGRUENCES OF SMALL DEGREE IN G(1,4) - PFAFFIAN LINKAGE IN CODIMENSION-3 AND APPLICATIONS TO CONGRUENCES, Communications in algebra, 26(10), 1998, pp. 3267-3274
We introduce the notion of Pfaffian linkage in codimension three and g
ive sufficient conditions for the linked variety to be smooth. As a re
sult, we are able to construct smooth congruences of lines in P-4 whos
e existence was an open problem.