A is as good as if not better than B
Explanations for this phrase I got are a bit controversial. Some say A≤B, some, A≥B, but others say it could be A≤B or A≥B depending on the situation.
The phrase "not better than" may mean "worse" or "almost the same." When you take the phrases "worse" and "almost the same," the sentence above expresses A≤B and A≥B, respectively.
The word "if" also has different meanings: concession and giving a hypothetical situation. When you take the "if" in the sentence shown as concession, the sentence seems to express A≥B.
I would like to know whether and how the sentence shown may be saying A≤B, A≥B, or A≤B or A≥B depending on the situation.
PS.
user867 pointed out that this phrase is a fixed idiomatic expression. I would like to know your thoughts about this.
Best Answer
That sentence always means "A is at least as good as B". (I guess in your scheme you'd represent that as A≥B, assuming that "more" is "better".)
The reason for this is that "if not X" means roughly "or maybe even X". For example, "many if not most people like summer better" means "many people, maybe even most people, like summer better". So your sentence can be rephrased as: