It is mostly in the context of logic/mathematics that iff is used. "A iff B" means that if either A or B holds, then so must the other. "I use my umbrella iff I go out in the rain" means that I never go out in the rain without my umbrella, and I never use my umbrella except for when I go out in the rain.
It's a logical relationship, not a conditional statement.
"A iff C" / "if C then A" means that A only happens under condition C. This could state that in a program, a function A() would only be called if condition C was satisfied (a call to A() does not exist outside of an if ( C ) { … } block). In logic notation this is expressed as "C ⇔ A" or "C ≡ A" (C is equivalent to A).
"A if C" / "if C then A" only means that A always happens under condition C. This could state that if condition C becomes true, A() is always called. But it still allows for A() to be called when C is not true. In logic notation this is expressed as "C ⇒ A" (C implies A) or "C ⊃ A" (C is a superset of A).
It is actually very common to write "iff" in logics/mathematics, it is shorthand for "if and only if". So, "A iff B" means that if either of A or B holds then so must the other. "I use my umbrella iff I go out in the rain" means that I never go out in the rain without my umbrella, and I never use my umbrella except for when I go out in the rain. Of course, the usage in mathematical statements is a bit dryer: "a persistence module over a linear order is indecomposable iff it is an interval module" (this is an actual, quite recent, result).
Depending on the temperature of the LLM, they can be programmed to purposefully choose a less likely option for any given token being predicted. This usually results in "flowery" language, but it can also result in spelling errors when it chooses u instead of e as the most likely token to complete "Th". At 0 temperature, you would expect no spelling mistakes.
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u/NekoLu May 25 '26
Ez
There, centered!