11 ms·
I fail to see the ingenuity, or even any common sense in this. If to "run" the algorithm you are required to have as many stones as the end result (actually qui
by MarcusBrutus 13y ago
I fail to see the ingenuity, or even any common sense in this. If to "run" the algorithm you are required to have as many stones as the end result (actually quite more if you count those spent on "evil" holes), you might as well spread out on the ground 34 groups of stones with 7 stones in each group and just count them. Or create a 34X7 rectangle and count the stones. So I dare say we differ a lot from the Ethiopian shaman. Reality doesn't always conform to the PC narrative of how all civilizations are equal. Unless you are a sociology major that is.
- alanctgardner2 13y agoCorrection: to run the algorithm you're required to have at least as many stones as the end result. That's like saying because MAX_INT is set, math on computers is pointless. Any physical process will have a finite upper bound on the size of the result. I agree that this isn't a remarkably efficient algorithm, but it is novel (it's completely unintuitive to the average reader), and it has a sound basis in mathematics. For the people who employed it, it was an efficient algorithm, or else they wouldn't have continued to use it. Nobody is proposing you're not as smart because you don't do math this way (although frankly, I doubt if you would have derived this by yourself, under the same conditions). On a side note, I strongly recommend 'Guns, Germs and Steel'. I've been knocked for mentioning it before because it's a pop-sci book, but it explains why cultures 'progressed' at different rates because of largely environmental factors. This might help you overcome your ridiculously defensive bias against African cultures.
- deleted 13y ago[deleted]
- MarcusBrutus 13y agoIt couldn't have been efficient since it is patently idiotic. Just spread 34 groups of 7 stones each on the ground and count them! That's all you have to do. No algorithm at all, just symbolic logic, and you need fewer stones, and probably takes less time as well. The only way to use this algorithm to portray the mathematical prowess of native Ethiopian culture in some positive way is to argue that the Shamans purposefully used this algorithm to obfuscate the process and maintain the life style and privileges of the priestly class. I dare you to claim with a straight face that this "algorithm" is even remotely comparable to what the Greeks did, e.g. Archimedes' proving, PROVING I repeat, in a mathematically rigorous way, in the 3rd century BC, that a sphere has 2/3 the volume and surface area of its circumscribing cylinder.
- DanBC 13y agoYou're getting a bit hung up on the stones. This algorithm allows people to multiply two numbers if all they can do is multiply and divide by 2, and add. > It couldn't have been efficient since it is patently idiotic. And yet is it so efficient it is how computers multiply.
- mistercow 13y ago>This algorithm allows people to multiply two numbers if all they can do is multiply and divide by 2, and add. Yes, and the algorithm of making N groups of M and then counting allows people to multiply if all they can do is count. And they will do it far faster than the shaman every time. >And yet is it so efficient it is how computers multiply. No, it isn't.
- DanBC 13y ago> Yes, and the algorithm of making N groups of M and then counting allows people to multiply if all they can do is count. And they will do it far faster than the shaman every time. So why didn't they?
- mistercow 13y agoI don't know. I notice that I am confused, so I know that between my existing beliefs and the details of this story, something important is fictional. My strongest guess is that it's the stones. In any base > 1 the algorithm is efficient. In unary (counting stones), it inefficient to the point of being nonsensical. So my guess is that this was not used by counting stones, but with some form of positional number system, and that in the retelling, stones have been added as a way to make it sound more "tribal". Edit: Alternatively, it may be the idea that they're doing this exactly. If the doubling side is done by rough estimation (eyeballing the size of the piles), it might be faster.
- alanctgardner2 13y agoI don't get why there has to be a 'positive' or 'negative' angle on the story. You're trying to compare two different cultures in terms of which is 'better', which is a completely pointless goal. Nobody is saying native Ethiopians developed abstract mathematics as complicated as those of Greek, Arab, Chinese, etc. cultures.
- shawnz 13y agoOkay, first and foremost, the algorithm obviously was never actually used in the way this story describes, because it is totally ridiculous and that is not even the point of the article. But let's say it was. In saying that the shaman knows how to put two sets of 7 stones in a particular pile, it is implying that the shaman also knows how to put 34 sets of 7 stones in a particular pile. He also knows how to count them, so the problem is already solved. What he is doing is a bit more "rube goldberg" than novel. It may have parallels with some real algorithm for multiplication, but it is certainly not a very direct representation of it.
- DanBC 13y agoDoes it help if you don't call them "stones" but call them "bits"? (https://en.wikipedia.org/wiki/Multiplication_algorithm#Peasant_or_binary_multiplication https://en.wikipedia.org/wiki/Multiplication_algorithm#Peasa...)
- mchouza 13y agoNo, the algorithm as described is very different from binary multiplication. It requires a number of stones proportional to the result, while the number of bits required when doing binary multiplication is polylogarithmic. It's a big difference: 1000 * 1000 would require 1000000 stones if done with the "Ehiopian algorithm", but it can be done with less than 1000 stones by using normal binary multiplication.
- yaakov34 13y agoNo, it absolutely does not help. In the algorithm you are citing, the numbers never leave their binary representation; there is no counting of the units that make up the number. The step of multiplying by 2 is done by shifting the binary representation of the number, which is not the way that this supposed "Ethiopian algorithm" works. The long multiplication algorithm (in binary or not) has complexity O(log(NM)), where N and M are the numbers to be multiplied, while this algorithm has complexity O(NM), and also gets there in a roundabout way. This algorithm is totally pointless if you're not going to work with a positional notation for the number; I am sure it was never used in the way described, with stones. Anyone capable of understanding the problem in the first place - 34 goats, 7 pieces per goat - would count out the price - here is 7 for the first goat, 7 for the next, etc. - and tell the shaman to take a hike. This story amounts to calling Ethiopians idiots for taking an algorithm suited for positionally represented numbers - or at least numbers in some kind of a concise representation - and using it in a totally unnecessary way with numbers represented as groups of stones, and not understanding the pointlessness of all the drudgery.
- DanBC 13y ago> Unless you are a sociology major that is. John H. Lienhard is Professor Emeritus of Mechanical Engineering and History, getting his PhD from UC Berkeley. > I fail to see the ingenuity, You can't see something ingenious with probably illiterate people using a different base to multiply numbers? As per the Wikipedia link posted by vilhem_s "The method as interpreted by conversion to binary is therefore still in wide use today as implemented by binary multiplier circuits in modern computer processors."
- MarcusBrutus 13y ago> John H. Lienhard is Professor Emeritus of Mechanical Engineering and History, getting his PhD from UC Berkeley. Close enough for me. Frankly I doubt that he honestly believed every word he wrote. People in high places have to routinely perform public worship of the PC god, "all cultures are equal", etc. Regarding the "ingenuity" see me reply above: https://news.ycombinator.com/item?id=6502665 https://news.ycombinator.com/item?id=6502665
- skunkworks 13y agoYou're taking a cute fictional story and running wild with it to somehow fit your weird anti-PC agenda. No one here, including the original article's author, is claiming that this is evidence of cultural equality. Way to waste your energy.
- judk 13y agoThe article: > So how do we and that Ethiopian shaman differ? Very little, I reckon. > Very little indeed. Of course, I wouldn't be surprised if he makes fewer mistakes than we do. The article clearly dumbs down (or misunderstands)the algortihm, insulting the audience's intelligence to make a feel-good claim about the arithmetic talent of "uncivilized" Ethiopians, and is accidentally racist in the process.
- fnordfnordfnord 13y agoGive Lienhard a break. IIRC He's a mechanical engineer; so, prior to learning of Ethiopian Multiplication, he probably used hammers to count with.
- cpleppert 13y agoIt is simply a way of performing multiplication without requiring a positional notation system. If you don't have that this allows you to do multiplication of very large numbers assuming you can divide and multiply by 2. You could do this on paper but usually you would have objects that would represent number units used in the culture such as 50,10,5,1 etc. So your objection that you might as well count them out is simply not true, this method is faster than what you suggested. >>Reality doesn't always conform to the PC narrative of how all civilizations are equal. Unless you are a sociology major that is. I'm not sure what your point is. True positional numerals have a long cultural history that doesn't lend itself easily to an analysis of which culture performed math better.
- deleted 13y ago[deleted]
- yaakov34 13y agoThe algorithm actually does make sense for positional systems (or compact notations in general). Think of long multiplication: it assumes you can multiply by a one-digit number, and lets you get from there to multiplying by a many-digit number. This is the same thing, but it only assumes you can multiply by two, instead of by any one-digit number. So this is a variant of long multiplication, and equivalent to performing long multiplication in binary. But it only makes sense if you have a compact representation of your numbers, since otherwise you may indeed just perform the multiplication directly by counting out 7 stones for the first goat, 7 for the next, and so on. It is the version described by Lienhard - which involves counting out the whole number anyway, which you could just as easily do without any special algorithm - that is pointless.
- mistercow 13y agoHow is this method faster than counting them out, when the end result is 238 stones that you have to count in order to know the answer?
- DanBC 13y ago
- pacala 13y agoThe algorithm only requires 12 holes, and scales the number of holes logarithmically. As opposed to make one group per unit, which scales the number of groups linearly. Less holes, less work, win. If you squint your eyes a bit, you can even imagine where this comes from. To avoid creating too many holes, you start with a group of 7 stones, then double them, then again, until you "double" them 34 times. Obviously 34 is not a power of two, so you need some extra machinery to make it work for non powers of two.
- VLM 13y agoI have an algorithm that only takes 7 holes compared to your 12 which is seven bucks per sheep means make seven holes and shove 34 sheep into each money hole then count the total. Its an interesting Sunday morning to rack my brain trying to figure out which algorithm "wins" when parallel processed. Obviously 34 shamans working together could each count out seven dollars/rocks, but someone needs to count up all those rocks. There's an obvious token passing algorithm involving three shamans and I believe 7+34=41 rocks and 4 holes where one does a long count of the total and count++ every time upstream hands him a rock, then upstreams upstream does the same. So one dude counts to 34 using 34 rocks one time, the next dude counts to 7 (and does it 34 times) using 7 rocks, and the last dude counts every time dude 2 hands him a rock and never resets to zero (at least until done) giving him a total. You can tell scientists invented the original algorithm not engineers just by a simple observation of actually implementing the algo... "Yo shaman come over and mult 7 by 34 for me" "OK but how many rocks will I need to multiply this... do me a favor and whip out your iphone and google 7 asterisk 34 so I know a lower bound of how many rocks to bring to implement this algo.." The worst part of the whole discussion is it reads like a really extraordinarily bad stereotypical tech interview question. "So, I see you've got extensive experience on the job with Scala and Mysql and play framework, thats all very nice, but a major problem we often have here at BigCorp is sometimes we want to measure precisely 4 oz of rum but we only have a 3 oz and 5 oz cup and we were wondering what you thought of that ..." You know some kind of space alien anthropologist is going to hear this is how those ancient "humans" used to select their programmers and the space aliens who hear pop sci stories about human programmer interviews are going to think 1) We were insane/stupid 2) They're superior. Theres not much other reason for the whole story.
- ekm2 13y agoSo I dare say we differ a lot from the Ethiopian shaman. Reality doesn't always conform to the PC narrative of how all civilizations are equal How did you generalize from an Ethiopian shaman's unique method of calculation to the superiority of civilizations?
- bayesianhorse 13y agoI don't see a particular reason why one should mention "PC narrative of all civilizations being equal" in this context. This article is merely an example of how stone-age "technology" can perform a certain task. I also take issue with the automatism of accusing "political correctness". Nobody says civilizations are equal, there are numerous obvious differences. Somehow whenever I dig deeper and ask about what those people think, I get to hear/read profound racist undertones. The "PC" curse is really most common as a defense to accusations of racism. The actual problem arises when people go on to make value-judgements along ethnical boundaries (racism). And then they go even further, using these not necessarily well founded judgements to pose "scientific facts" about how one ethnicity is genetically superior (because they believe all differences between two sets of humans have to come down to genetics/evolution)and thus are somehow entitled to more wealth than another ethnicity. Their is no right to wealth and no birth right to it. That does not however imply a redistribution of wealth in the slightest way. There are strong factors which contributed to the economic rise of Europe "first" and which have nothing to do with human genetics. Agriculture benefits from certain climates and soil conditions (ask the mayans about their collapse...). It also benefits a lot from domesticateable animals, and most animals are not nearly as well suited as for example horses and cows. Then the coastlines and rivers in Europe have shown to be much more conducive to commerce (before industrialization) than in Africa or America. Systems are complex. Don't simplify them to justify judgements.
- MarcusBrutus 13y agoI wouldn't normally want to comment on that since it's not relevant to the original thread but what exactly do you mean "no birth right to it"? Like, I can't bequeath anything to my kids cause that would confer an "unfair" advantage on them? Or maybe we need a "fair" inheritance tax. Like 95% maybe? Somehow it is your political / worldview bias that's transparent in your post, not mine. I said nothing about genetic overall superiority although it is plainly evident to anyone not blinded by PC that some peoples are genetically more likely to produce sublime music or advanced mathematical frameworks / complex works of art or advanced technology just like other peoples are genetically more likely to be stronger, better jumpers, runners, sturdier and so on. Environment certainly played a role but after many hundreds or even thousands of generations the genetic makeup of a people changes as well (as an aggregate statistical entity). I've no doubt these genetic differences were non-existent when we were all together in the primordial soup but we've moved past that phase and these differences now exist. I am saying nothing about overall superiority and certainly nothing about rights of individuals. If you make the extraordinary claim that the genetic makeup of a people played no role in the difference of achievements between cultures the onus is on you to prove a negative. Explain why we take it for granted that people of Samoan heritage are huge but it's somehow racist to argue that hey, that DNA thing may be affecting brain cells as well and not just bones / muscle tissue.