Plunbing Question, to trap or not to trap?

[Engineer Guy]

Hee hee, well no Plumber 'pedigree' here! I muddled through building much of my own House, but was told that 'Island Vent' term by an actual Plumber. The Vent works well, and represented one less possible Code hassle when getting my 'fine' plumbing work signed off. I'd never thought of using that solution in a TT/CT, so I'm glad an install was shared on this Forum.

[bobhenry]

When I put the sink in "Chubby" I never even thought, I just used a small 1 1/4 vanity sink trap. The only reason I used the trap was to get the plumbing down stub very tight into the corner of the cabinet to gain more storage space in the cabinet.