And old Irish maths teacher joke "What is t(h)ree t(h)rees?" "9?" "No. A small forest." :)
"mia amikaro" is something like "my circle of friends". The two words are effectively interchangeable, but you might choose "amikaro" if you wanted to stress group membership or exclusivity: "vi ne estas en mia amikaro".
Wouldn't it take an 'arego de arboj' to deserve the word 'forest'? I wouldn't dream of calling a mere group of trees a forest.
Actually, it's beyond subjective interpretation. Think of it as a set rather than several individuals. Don't think of the arboj, but rather as an abstract collection structure.
Ekzemple, let's say you want to group together members in a household. The household is the aro; the set. Once that is established, you can begin to include household members. Few members, many members, one member... it doesn't matter. What matters is that there is an abstract set called the "household", and within that set is members.
As another example, I'll use the Python language for readability. Imagine the following scenario:
aro = 
aro += alialisto
No matter how many members exist in the list aro, be it just "Alico", both "Alico" and "Benito", or even merging in a whole other list, aro is still an abstract collection which can contain members. It doesn't suddenly become a collection when it achieves an arbitrary member count. :) I hope that helps.
No offence, I think the above is awesome. However...
You know you are among nerds when you see a post discussing Esperanto with analogies to set notation and Python. You know you are a nerd when you read and like the whole thing.
Your comment reminded me of Nerd Girl Problems, so I went to read a few and learned that they haven't updated in over a year.
So an arbaro can consist of three trees, but still, three trees do not make a forest. So, the translation must be a bit off the mark, or what?
For such specifics, I can't say that I'm the best candidate to directly answer. However, I will say that no specific definition of a forest is universally accepted. Hundreds of classification parameters are used around the world.
The takeaway here is that the more precise breakdown of "arbaro" is merely "arb" + "ar" + "o". Taken element by element, it's a tree group. Whether there are limits to culturally accepted use cases of "arbaro" in common parlance, though, I do not know.
All I was replying to above was that "aro" indicates a grouping, and that scope classifications aren't necessarily relevant to the truth value of the abstract group itself. For another example, take "bela". Words like "beleta" and "belega" exist as well, but those don't mean completely different things from "bela"; they merely specify further the scope (whether diminutive or augmentative) within the confines of "bela". In this case, I can imagine people using words like "arbarego" and "arbareto" depending on how they want to paint this abstract idea of a group of trees. Neither is totally different from "arbaro", though; just more specific.
Redakto: I just thought I'd point out that I actually don't like the inclusion of this phrase in Duolingo for this very reason. The direct translation would best be "A group of trees is a tree group", which is pointlessly redundant. I suspect this phrase was included to provide a means of teaching different forms with shared meaning; like "a cat which is red is a red cat". Frankly, there's nothing inherent to the elements "arb" or "ar" to indicate that there's an extra requirement. If such a requirement as "forest" often gets is imposed, then I'd assume it's just cultural.
Well, one can also simply say that, while Esperantists would like to banish arbitrariness from the language, it will be there if the language is to communicate at all. In this case, it sounds like Esperantists have chosen the idea of a forest, rather than a copse or a grove, as the idea indicated by this particular group word, arbaro. I imagine the word arbareto would convey what I conceive of as a copse pretty well to other Esperantists. I'm sure that other -aro words would convey a larger or smaller sense of number. Of course, Mr Zamenhof could have developed a series of suffixes to indicated specific numbers, like the prefixes of the metric system, but I think these more vague terms function much more nicely as a language.
So now I don't know whether to insist that 'A group of trees is a wood' should be accepted. Isn't the problem with English rather than Esperanto? I too tried first with 'copse' but that's specifically a small group of trees. Surely the most generic word is 'wood' though, because a forest is specifically a very large group of trees and so far as I understand the Esperanto word doesn't have that sense.
Basically arbaro cannot consist of three trees. It is just English doesn't have a simple word that expressed the concept of "aro" (совокупность). If the group of trees has a new quality that those trees don't have on their own (forest is more that just some trees) - it is "aro de arboj". And just some trees that grow somewhere aren't "aro". The same with other "aroj"
Kial "de" estas uzata anstataŭ "da"? Aro estas kolekto, kiu enhavas elementojn, ĉu ne? Simile kiel la frazo "listo da vortoj" por listo, kiu enhavas vortojn, kial "arbaro" ne estas aro, kiu enhavas arbojn, do "aro da arboj"?
Por uzi la prepozicion "da", necesas ke la antaŭa vorto enhavas ideon de kvanto. "Aro" estas tro nedefinita laŭ mi por uzi "da" kun ĝi, oni ne povas respondi al la demando "kiom da arboj estas tie ĉi?" per "aro".
Dankon! Mi komprenas nun. Tial mi vidis "aro da elementoj", kiam la elementoj nombreblas en la aro. Do por nenombreblaj aroj, oni devus uzi la prepozicion "de" anstataŭe, se mi prave komprenas.
If I wanted to refer to a group of kids, would either infanaro or geknabaro be acceptable?
Aro de aroj estas araro. Seems not all words, we can make, do exist.
Why would that not exist? It seems to me that a set of sets could be described as an araro.
Sennoma said:" I can imagine people using words like "arbarego" and "arbareto" depending on how they want to paint this abstract idea of a group of trees." So, would a grove (small group) of trees be an arbareto? Or would that be a small tree?
An «arbareto» would be a small grove of trees. An «arbetaro» would be a forest of shrubs. And I guess an «arbetareto» would be a grove of shrubs?
How do you say woods as in: "The Hickaly Woods has a giant skeleton in it." That's a Zelda refrence, in case you didn't know. But the question is serious.
If "arbaro" is forest, then what is an "orchard"? "Forests" and "orchards" differ not so much by size as by "intent": forests are natural, while orchards planted in an organized way for harvesting.
Orchards is a place with fruit trees, so: fruktarbejo or fruktarbaro probably is a good option? :)