expert system inference engine whenever a value is changed referring now to fig1 polymer is conveyed from a polymerization vessel not shown in the direction of the arrow through suitable piping 1 to a spinning pack 2 containing mult iorificed spinneret 3 extruded from the spinneret orifices to form a group of filaments 4 which pass downwardly as a yarn bundle 4a and pass around puller roller 5 and advance to roller 6 where the yarn bundle splits into a left threadline 7 and right threadline 7 39 as shown each advancing threadline then passes by roller guides 8 and 8 39 and is wound onto bobbins to form yarn packages 9 and 9 39 the hardware associated with windup of ends 7 and 7 39 is referred to broadly as left windup unit lwu and right windup unit rwu respectively of course many intermediate processes may occur during passage of the filaments from spinneret 3 to packages 9 and 9 39 such as heating cooling drawing interlacing liquid finish application etc electronic sensing devices brk 10 are used to sense the presence or absence of a yarn bundle 4a sensing devices 11 associated with the lwu and 11 39 associated with the rwu sense presence.