In knot theory, the Thurston-Bennequin number, or Bennequin number, of a front diagram of a Legendrian knot is defined as the writhe of the diagram minus the number of right cusps. The maximum Thurston-Bennequin number over all possible front diagrams of the Legendrian knot is a Legendrian isotopy invariant of the knot.

References

• Maximal Thurston-Bennequin number at The Knot Atlas
• Lee Rudolph (1997). "The slice genus and the Thurston-Bennequin invariant of a knot". Proceedings of the American Mathematical Society 125 3049 3050. 1443854.

| doi = 10.1090/S0002-9939-97-04258-5 }}