One more direct example invokes a legal fiction known as labud:
If a cross-beam was drawn away or suspended [at a distance of] less than three handbreadths [from the walls of the alley] there is no need to provide another beam, [but if the distance was] three handbreadths another beam must be provided.
It is then argued whether 3 or 4 handbreadths is the correct amount. What is described here is a beam which stretched over the entrance to an alley but which does not reach one or both sides. The can happen if there are pins in wall which the beam is resting on, or if it is suspended from the ground T-shaped by a pole in its middle. Either way the principle of labud is invoked. Literally meaning “joined” it states that if the gap is small enough (less than 3 or 4 handbreadths depending on which authority you follow) it is treated as if it is actually joined to the wall.
A similar principle known as chabut (“pressed down”) works in the vertical realm – that is pins which are inclined and holding up a beam are treated as if they are level in terms of the height of the beam (making legal a beam suspended too high on them).
These kinds of legal fictions make complicated situations a bit more reasonable. A kind of “benefit of doubt” made possible.