We derive an explicit fornoula for the computation of a Vassiliev-type invariant of an apparent contour introduced recently by Ohmoto and Aicardi using appropriate linking numbers of its Legendrian lift. Our formula does not require the construction of the Legendrian lift and only takes into account the nodes, the cusps, the extremal points and the orientation of the apparent contour. In this way the computation can be implemented into a Computer program; we demonstrate its use with some examples. (C) 2008 Elsevier B.V. All rights reserved.
Bellettini, G., Beorchia, V., Paolini, M. (2009). An explicit formula for a Bennequin-type invariant of apparent contours. TOPOLOGY AND ITS APPLICATIONS, 156(4), 747-760 [10.1016/j.topol.2008.09.011].
An explicit formula for a Bennequin-type invariant of apparent contours
BELLETTINI, GIOVANNI;
2009-01-01
Abstract
We derive an explicit fornoula for the computation of a Vassiliev-type invariant of an apparent contour introduced recently by Ohmoto and Aicardi using appropriate linking numbers of its Legendrian lift. Our formula does not require the construction of the Legendrian lift and only takes into account the nodes, the cusps, the extremal points and the orientation of the apparent contour. In this way the computation can be implemented into a Computer program; we demonstrate its use with some examples. (C) 2008 Elsevier B.V. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
