"all but at most one" - What does it mean?

Question

I came around this one just now and I can't tell the meaning of this sentence by the context.

no new vehicle is used unless all but at most one other vehicle has at
  least 50% of its time scheduled

Does it mean something like "all are, but one is not"?

slim · Accepted Answer

"At most one" means zero or one.

"All but at most one" means "all" (all minus zero) or "all but one" (all minus one).

But wow, what a confusing sentence!

Mike Lyons · Answer

if this had been read aloud by the author before publishing it may have been revised to say:
"No new vehicle is used until only one remains unused."

cxma · Answer

for example, x=0 at all but at most one point in (a,b) means all the x are zeros except at most one point in (a,b) may be non-zero.

3 Answers