My Salam number is 4 via the following path:

Valerio Cappellini coauthored with Fabio Benatti − MR2027615 (2005e:81072)
Fabio Benatti coauthored with Roberto Floreanini − MR1437062 (98d:82032)
Roberto Floreanini coauthored with Ergin Sezgin − MR1007753 (90k:81116)
Ergin Sezgin coauthored with Abdus Salam − MR0708214 (84g:83046)