2 ms·

What is "the rule of three"? I have never heard of it, and Googling it was not helpful. Conspiracy sites and rules for fiction writers and things.

AnimalMuppet 2y ago
Dunno. The only programming rule of 3 I know is that, in a C++ class, you provide a destructor, a copy constructor, and an assignment operator. But that doesn't fit either, because it's not really algebra, and every grandma certainly does not know it, and it doesn't fit in a Lisp article anyway.
anthk 2y ago
The basic proportion matching formula which is just a linear equation in disguise. a/b = c/d, we know a, b and c, solve for d, which is cb / a. As I said, every grandma did that to guess some percentages. Thus, if anyone can grasp that, he/she is ready for Algebra.
- lproven 2y ago
  Never heard of this before, and no, I do not think my own mother could do this. Again: I think you badly underestimate how hard this stuff is.
  - anthk 2y ago
    Ever? A book costs $20. How many books could you get with $200? That's it. Even my granma living in a remote village understood it.
_yb2s 2y ago
The person you are replying to clearly stated that every grandma knows this, and yet you seem to have given up without even trying to ask a grandma.
- lproven 2y ago
  Well, this is true. I am 56, and my last living grandmother died over 30 years ago. I became a father 5 years ago, so strictly, my mother is a grandmother. I could ask her, but I am very confident she does not know. I have a science degree, and I just barely scraped through a statistics 101 course with great difficulty. I am pretty smart; I speak 6 foreign languages, and I have held down a career in software for approaching 40 years now, by understanding hard stuff and making it work, or documenting it, or explaining it. But I find algebra hard, just scraped through a mathematics 'O' level in 1986 by taking corrective classes and resitting the 1985 exam that I failed. I stand by what I said. I've never heard this rule. Looking at the Wolfram explanation, I could do that, yes. But I've never heard of this, and I am pretty confident my mother could not do this.
  - _yb2s 2y ago
    I don't think it came across clearly but I was teasing the commenter you were replying to (and not you) for making an absurd claim in a confusing, sexist, and ageist way. Although my own grandparents are also dead, I know quite a few grandmas, including my stepmom (who had a ~5 decade career as a software engineer) - that are brilliant mathematicians and/or coders - so I take exception to the idea of using the word grandma as a stand-in for an ignorant person. Also, every person educated through public school in a wealthy country that isn't mentally disabled knows actual algebra and has studied it for 6+ years, not just the "rule of 3" whatever that is. However, I do want to say something about listing out your qualifications and experience like you did on here... in the petty power struggles and trolling on the internet it does the exact opposite of what it seems like it should. It's putting the other person in charge of deciding if you are "good enough" to participate or have an opinion, by implicitly making an effort to convince them and asking them to judge you. Your opinion and reasoning carry more weight on their own, without arguing why you should have the right to have them.
    - lproven 2y ago
      Hmmm. Well, if we all misread you, ISTM that you also misread me. What I was trying to say was: "I am pretty smart, but I can't do this." Which means: "different people are smart in different ways." Which means: "what is no problem for Lisp coders can be a pretty big problem for other folks."
cwmoore 2y ago
Cross-multiplying related proportions to find the fourth value: https://mathworld.wolfram.com/RuleofThree.html https://mathworld.wolfram.com/RuleofThree.html

AnimalMuppet 2y ago

Dunno. The only programming rule of 3 I know is that, in a C++ class, you provide a destructor, a copy constructor, and an assignment operator. But that doesn't fit either, because it's not really algebra, and every grandma certainly does not know it, and it doesn't fit in a Lisp article anyway.

anthk 2y ago

The basic proportion matching formula which is just a linear equation in disguise. a/b = c/d, we know a, b and c, solve for d, which is cb / a. As I said, every grandma did that to guess some percentages. Thus, if anyone can grasp that, he/she is ready for Algebra.

lproven 2y ago
Never heard of this before, and no, I do not think my own mother could do this. Again: I think you badly underestimate how hard this stuff is.
- anthk 2y ago
  Ever? A book costs $20. How many books could you get with $200? That's it. Even my granma living in a remote village understood it.

_yb2s 2y ago

The person you are replying to clearly stated that every grandma knows this, and yet you seem to have given up without even trying to ask a grandma.

lproven 2y ago
Well, this is true. I am 56, and my last living grandmother died over 30 years ago. I became a father 5 years ago, so strictly, my mother is a grandmother. I could ask her, but I am very confident she does not know. I have a science degree, and I just barely scraped through a statistics 101 course with great difficulty. I am pretty smart; I speak 6 foreign languages, and I have held down a career in software for approaching 40 years now, by understanding hard stuff and making it work, or documenting it, or explaining it. But I find algebra hard, just scraped through a mathematics 'O' level in 1986 by taking corrective classes and resitting the 1985 exam that I failed. I stand by what I said. I've never heard this rule. Looking at the Wolfram explanation, I could do that, yes. But I've never heard of this, and I am pretty confident my mother could not do this.
- _yb2s 2y ago
  I don't think it came across clearly but I was teasing the commenter you were replying to (and not you) for making an absurd claim in a confusing, sexist, and ageist way. Although my own grandparents are also dead, I know quite a few grandmas, including my stepmom (who had a ~5 decade career as a software engineer) - that are brilliant mathematicians and/or coders - so I take exception to the idea of using the word grandma as a stand-in for an ignorant person. Also, every person educated through public school in a wealthy country that isn't mentally disabled knows actual algebra and has studied it for 6+ years, not just the "rule of 3" whatever that is. However, I do want to say something about listing out your qualifications and experience like you did on here... in the petty power struggles and trolling on the internet it does the exact opposite of what it seems like it should. It's putting the other person in charge of deciding if you are "good enough" to participate or have an opinion, by implicitly making an effort to convince them and asking them to judge you. Your opinion and reasoning carry more weight on their own, without arguing why you should have the right to have them.
  - lproven 2y ago
    Hmmm. Well, if we all misread you, ISTM that you also misread me. What I was trying to say was: "I am pretty smart, but I can't do this." Which means: "different people are smart in different ways." Which means: "what is no problem for Lisp coders can be a pretty big problem for other folks."

cwmoore 2y ago

Cross-multiplying related proportions to find the fourth value: https://mathworld.wolfram.com/RuleofThree.html https://mathworld.wolfram.com/RuleofThree.html