I came across the following tech. presentation, and the first sentence annoys me: "0.5 to 0.55 is tops for similar problems".
Wouldn't it be better to write "is best" because "is tops" doesn't sound correct to me. Google also said that this phrase isn't too common.
What's right?
It certainly doesn't seem grammatically correct. I am unfamiliar with the material but presumably this should be correctly phrased as
0.5 to 0.55 is the upper limit for similar problems
or
the upper bound for similar problems is between 0.5 and 0.55
or similar.
As a native English speaker I find the original wording confusing and non-standard.
In a non-mathematical context the phrase does have more common meaning...
as @Dusty says things like "It'll cost you 5 pounds, tops" - meaning it will cost no more than 5 pounds.
Also, "it's the tops" is a somewhat old-fashioned way of saying something is the best. In more modern slang people will say "top" in a context like
"How was the gig?"
"Oh it was top mate"
While both answers above are correct another usage of tops is as an adjective meaning excellent, great or fantastic, as listed here by the OED1. Although this usage is highly informal and regional, common chiefly only in Dublin, New Zealand and Australia.
The Merriam-Webster online dictionary defines tops as an adverb:
: at the very most //will cost $50, tops
So as El Ronnoco says, it's grammatically incorrect in your example.
A more appropriate sentence using "tops" could look like this:
for similar problems, the upper limit is 0.5 to 0.55 F1, tops.
