Trap (plumbing)
In plumbing, a trap is a U-, S-, or J-shaped pipe located below or within a plumbing fixture. An S-shaped trap is also known as the S-bend invented by Alexander Cummings in 1775 but became known as the U-bend following the introduction of the U-shaped trap by Thomas Crapper in 1880. The new U-bend could not jam, so, unlike the S-bend, it did not need an overflow. The bend is used to prevent sewer gases from entering buildings. In refinery applications, it also prevents hydrocarbons and other dangerous gases from escaping outside through drains.
The most common of these traps in houses is referred to as a P-trap. It is the addition of a 90 degree fitting on the outlet side of a U-bend, thereby creating a P-like shape. It is also referred to as a sink trap because it is installed under most house sinks.
Because of its shape, the trap retains a small amount of water after the fixture's use. This water in the trap creates a seal that prevents sewer gas from passing from the drain pipes back into the occupied space of the building. Essentially all plumbing fixtures including sinks, bathtubs, and toilets must be equipped with either an internal or external trap.
Trap (printing)
Trap on a press is the ability of a printed ink to accept the next printed ink compared to how well paper accepts that ink. Registration is when all printed images are lined up over one another. Trapping is a term originally used as a measure of how well one ink printed on top of another. With the advent of Pre-press Software the term was misused to describe the compensation for misregistration between printing units on a multicolor press that was traditionally known as "Chokes and Spreads". This misregistration causes unsightly gaps or white-space on the final printed work. Trapping involves creating overlaps (spreads) or underlaps (chokes) of objects during the print production process to eliminate misregistration on the press.
Background
Misregistration in the graphical workflow may be caused by a number of reasons: inaccuracies in the image setter, instability of the image carrier (e.g., stretch in film or plate), inaccuracy in the film-to-plate or film-to-film copying steps, instability of the press, instability of the final media, and human error.
Slow play
Slow playing (also called sandbagging or trapping) is deceptive play in poker that is roughly the opposite of bluffing: betting weakly or passively with a strong holding rather than betting aggressively with a weak one. The flat call is one such play. The objective of the passive slow play is to lure opponents into a pot who might fold to a raise, or to cause them to bet more strongly than they would if the player had played aggressively (bet or raised). Slow playing sacrifices protection against hands that may improve and risks losing the pot-building value of a bet if the opponent also checks.
David Sklansky defines the following conditions for profitable slow plays:
