Actual Proof 1+1=2

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  • Опубліковано 15 лис 2024
  • Become a Math Master With My Intro To Proofs Course! (FREE ON UA-cam)
    • Intro To Math Proofs (...
    This video presents a clear and concise proof of why 1+1 equals 2, a fundamental concept in mathematics. It breaks down the logic and reasoning behind this basic equation, making it understandable for anyone interested in math.
    🙏Support me by becoming a channel member!
    / @brithemathguy
    #math #brithemathguy #mathematics
    This video was partially created using Manim. To learn more about animating with Manim, check out:manim.community
    Disclaimer: This video is for entertainment purposes only and should not be considered academic. Though all information is provided in good faith, no warranty of any kind, expressed or implied, is made with regards to the accuracy, validity, reliability, consistency, adequacy, or completeness of this information. Viewers should always verify the information provided in this video by consulting other reliable sources.

КОМЕНТАРІ • 693

  • @BriTheMathGuy
    @BriTheMathGuy  9 місяців тому +99

    🎓Become a Math Master With My Intro To Proofs Course! (FREE ON UA-cam)
    ua-cam.com/video/3czgfHULZCs/v-deo.html

    • @Ostup_Burtik
      @Ostup_Burtik 9 місяців тому

      First

    • @cloverisfan818
      @cloverisfan818 9 місяців тому

      Actually we can prove 1+1=2 by proving lim x->1 x+1=2, using delta epsilon

    • @krzysztofszczepanik8380
      @krzysztofszczepanik8380 9 місяців тому +1

      You used addition in your definition of addition

    • @GEMSofGOD_com
      @GEMSofGOD_com 9 місяців тому

      And a bit more in, a giga condensed form, on my website

    • @India_Pakistan1
      @India_Pakistan1 9 місяців тому

      ​@@krzysztofszczepanik8380true

  • @maxhagenauer24
    @maxhagenauer24 9 місяців тому +1827

    That hit hard when he said "If you really want to up your math game..." at the end of the video where he explains why 1 + 1 = 2.

    • @samueldeandrade8535
      @samueldeandrade8535 9 місяців тому

      What do you mean? Are you being ironic? I hope so, because this Bri, so called "The Math Guy", is the most intellectually dish0n3st math youtuber out there.

    • @GEMSofGOD_com
      @GEMSofGOD_com 9 місяців тому +8

      Bri's Mozart!

    • @samueldeandrade8535
      @samueldeandrade8535 9 місяців тому +7

      Hit hard? Because is s1lly af, right?

  • @nikolavulic-t9x
    @nikolavulic-t9x 5 місяців тому +753

    This is what the teacher expects you to do when they say "show your work"

    • @throughthoroughthought8064
      @throughthoroughthought8064 2 місяці тому +20

      I always enjoyed randomly inserting the phrase "and then a miracle occurred here..."

    • @nikolavulic-t9x
      @nikolavulic-t9x 2 місяці тому +9

      ​@@throughthoroughthought8064 lmao, i always did 90% of the stuff in my head, not even on tests just in schoolwork and the teacher would conplain

    • @Allyfyn
      @Allyfyn 2 місяці тому +5

      No, it's really not hard at all.

    • @taco6444
      @taco6444 Місяць тому +2

      It was revealed to me in a dream

    • @amongusmappingAUM
      @amongusmappingAUM Місяць тому +2

      @@Allyfyn This comment was obviously a joke, in case you didn’t know that.

  • @Gelster
    @Gelster Місяць тому +152

    This is the math equivalent of having to meet the minimum 1000-word count in your essay

  • @GlorifiedTruth
    @GlorifiedTruth 9 місяців тому +3029

    I have spent the last 40 years of my life trying to disprove this postulate. I graciously accept defeat at your hands, sir. SIGH.

    • @alien3200
      @alien3200 9 місяців тому +73

      You just wasted 40 years of your life, doing nothing 😊

    • @LeoV6502
      @LeoV6502 9 місяців тому +179

      0(1+1)=0(2+1)
      Cancel the zeros out!

    • @justsaadunoyeah1234
      @justsaadunoyeah1234 9 місяців тому +134

      @@LeoV6502 Illegal! I shall report you to the Math Police!

    • @yesImbob
      @yesImbob 9 місяців тому +49

      @@LeoV6502uhhh that’s not how it works

    • @LeoV6502
      @LeoV6502 9 місяців тому +7

      Mua ha ha ha ha haaah!!!

  • @weo9473
    @weo9473 9 місяців тому +414

    Meanwhile john hush proving 1=2 in every single way possible 🗿

    • @ilmionomenonloso
      @ilmionomenonloso 8 місяців тому +8

      That looks like a rather immediate task: there are no such ways

    • @ayuballena8217
      @ayuballena8217 6 місяців тому +40

      @@ilmionomenonlosothey’re all division by 0

    • @tri99er_
      @tri99er_ 6 місяців тому +9

      @@ayuballena8217 of course they are…

    • @ayuballena8217
      @ayuballena8217 6 місяців тому +1

      @@tri99er_ exept…

    • @midahe5548
      @midahe5548 Місяць тому +4

      @@ayuballena8217 except if we assume that every solid in 3 (or more) dimentions are mesureable :)

  • @gheffz
    @gheffz 9 місяців тому +244

    This "logic" proof could be written in a computer language called Prolog:
    _% Base case: Adding 0 to any number N results in N._
    plus(0, N, N).
    _% Recursive case: To add A and the successor of B, we first add A and B, then find the successor of the result._
    plus(s(A), B, s(C)) :- plus(A, B, C).
    ?- plus(s(0), s(0), s(s(0))).

    • @decaydjk8922
      @decaydjk8922 9 місяців тому +21

      And that is basically how arithmetic is defined in logic programming

    • @mskiptr
      @mskiptr 8 місяців тому +14

      And here's a similar thing but for the programming language and proof assistant, Idris:
      data Nat : Type where
      Z : Nat
      S : Nat -> Nat
      one, two : Nat
      one = S Z
      two = S one
      plus : (a : Nat) -> (b : Nat) -> Nat
      plus a Z = a
      plus a (S b') = S (plus a b')
      data Equals : (a : ty) -> (b : ty) -> Type where
      EqualityIsReflexive : (x : ty) -> Equals x x
      theProof : Equals (plus one one) two
      theProof = EqualityIsReflexive two
      This doesn't need any sophisticated reasoning because `plus one one` simply evaluates to `S (S Z)` and so is already the same thing. The type | proof checker can verify it mechanically.
      Also, if I were to use the standard library just these two lines would do the trick:
      theProof : 1 + 1 = 2
      theProof = Refl

    • @gheffz
      @gheffz 8 місяців тому

      @@mskiptr Excellent. Yes. Question Idris or Agda?

    • @mskiptr
      @mskiptr 8 місяців тому +1

      @@gheffz To be honest I don't have much opinion on Agda because I haven't really tried it (yet). It seems to have a bit more active community around it and I would guess the tooling should be less janky. Also, from what I've seen it's more focused on maths while I'm overall more interested in applying type theory to CS concepts. Oh, and then there are the fancy symbols used everywhere. I kinda like the idea but it has a massive potential to be really annoying and ugly.

    • @user-tk2jy8xr8b
      @user-tk2jy8xr8b 2 місяці тому +1

      @@gheffz Idris for the programmers, Agda for the scientists :)

  • @throughthoroughthought8064
    @throughthoroughthought8064 2 місяці тому +97

    My Second-grader says "nu-uh." And I can't disagree with them.

  • @Bodyknock
    @Bodyknock 2 місяці тому +26

    0 is very often included as a Natural Number when you are using set theory as the underlying basis since the Naturals are then defined as being the set of all possible finite cardinalities, and since the cardinality of the Empty Set is 0 that makes it a Natural Number.
    Where 0 isn’t usually included as a Natural Number is when you’re working in Number Theory since 0 is an annoying exception in a lot of theorems involving factorization. It’s simply more convenient to define the Naturals as starting at 1 in that context so you don’t have to keep dealing with 0 as a special case.

    • @Nitnelav00
      @Nitnelav00 26 днів тому

      I have never seen 0 not included as a Natural Number. maybe because I'm only doing arithmetic?

  • @jacob_90s
    @jacob_90s 8 місяців тому +28

    It is interesting how often in science and math the most tangible things are often the hardest to define in abstract terms.

  • @Peacemaker8D
    @Peacemaker8D 8 місяців тому +51

    Wish these videos were out 12 years ago. Been wishing for an understandable explanation since high school, thank you so much!!!

  • @davidmadar8894
    @davidmadar8894 2 місяці тому +278

    The name of the video is miseading, in my opinion. This is not really a proof that 1+1=2, but a proof that the definition of addition presented here is consistent with the result "1+1=2". If it wasn't consistent, the conclusion had not been that 1+1 does not equal 2, but that our definition for addition is faulty. This kind of proof put the result as something we want to achieve, because we assume it is true intuitively but lack the formal tools to describe it: we try to build a system of axioms and definitions that will lead to the result we wanted it to lead, and than we prove we succeded. Therefore it is meaningless to say we "proved that 1+1=2". What we did was finding an extremely elegant definition for addition that is consistent with the intuitive idea we already had and just wanted a formal set of axioms that will lead to it. This definition, or an extension of it, might become interesting and useful when it comes to adding things we don't have intuition about, such as infinity.

    • @catbertsis
      @catbertsis 2 місяці тому +42

      Agreed. Axioms are supposed to be the basic self-evident truths, but there is no way that Peano axioms are more self-evident than the fact that 1+1=2.

    • @b3kstudio
      @b3kstudio Місяць тому +12

      The video proved that "1+1=2 under the Peano axioms", and mentioned that the Peano axioms give us natural numbers, that are identical to the natural numbers we intuitively know. Thus 1+1=2. Proving the equivalency of the two groups would be a different proof.

    • @catbertsis
      @catbertsis Місяць тому +25

      @@b3kstudio This video heavily implies that the Peano axioms are in some sense more fundamental that basic properties of natural numbers, without really explaining why. That's why it has left me a bit frustrated.

    • @b3kstudio
      @b3kstudio Місяць тому +6

      @@catbertsis I think it depends on how you look at it. You could argue, that there is nothing more fundamental than taking a pile of one sticks, and another pile of one sticks, and putting them together. But that happens to be the same as the Peano axioms. Which one is more fundamental? Piles of sticks, for which you need sticks, which are arguably quite complicated by themselves, or 4 laws that can be used to represent the same thing.
      In the end, I think saying "this pile is 1, and this pile is 2" then taking two piles of 1 and putting them together is not a worse proof in any way, than the one in the video. Because really, 1+1=2, because we defined 1 and 2 that way.

    • @davidmadar8894
      @davidmadar8894 Місяць тому +3

      @@b3kstudio formally. you are right, of course. But the motivation of such a proof is not to prove that 1+1=2, but to prove that Peano Axioms are worth something and not leading to results we don't want. From that point of view, "1+1=2" was the result we wanted to have and the Peano Axioms were the axioms needed to achieve that - they are the starting point from the point of view of Logic, but not from the point of you of what we really wanted to find.

  • @TheLuckySpades
    @TheLuckySpades 8 місяців тому +31

    So 0 or 1 being the initial natural is actually a big split in conventions, in ny experience German speaking areas were more likely to start with 1, French and English speaking with 0, though English was the most mixed of the bunch
    And this split goes back even before Peano pubished his formalization, he was actually beaten to the punch by Dedekind (his formalization is equivalent, but also harder to state and closer to second order logic than first order)
    In Dedekind's initial manuscripts he started at 0, but somewhere in the process he began starting it at 1, he never wrote down why he changed it, but if I were to guess, the way he was approaching proofs became more elegant and simpler to write after the change, others went with 0 because their approaches had the opposite side for elegance

    • @tri99er_
      @tri99er_ 6 місяців тому +2

      0 indeed is not always considered a natural number, but it can be included, if needed. Also this way of addition extends to every whole number, not just naturals, so it is accepted here for convenience.

  • @кирофф
    @кирофф 2 місяці тому +7

    0:20 at this point the 2 circles and the loading icon came together perfectly lol
    upd: maybe only in my phone

  • @EugeneKhutoryansky
    @EugeneKhutoryansky 25 днів тому +3

    You are assuming that s(1) = 2. You could argue that this is just a definition, but then we could just as easily say that "1+1=2" is just a definition.

    • @BriTheMathGuy
      @BriTheMathGuy  13 днів тому +1

      Yes, you’re exactly right! The successor of one is twi by definition. Addition is also a definition we have to say what we mean by these things, but I have not defined what one plus one equals that’s what we actually proved.

  • @revtheobbyist
    @revtheobbyist 9 місяців тому +17

    "you 'probably' agree with me"

  • @TheFruitNewt
    @TheFruitNewt 9 днів тому +1

    I'm fucking with my math teacher.
    "So if i'm trying to see if this is true, should i subtract 1 from both sides? [1+1=2], turning it into 1+1-1=2-1 or 1=1, which is true."

  • @jadengames.3662
    @jadengames.3662 6 місяців тому +1

    It's funny it's actually common sense if you think about it. Another way we could write the equation is more expansive. A=N B=M and C=B-1. Then writing A+B=1+(A+(B-1)) that plus one moves a few spots but if you can sub S for one you will always get that the left and right sides are equal.
    I should clarify it is simplistic the way you explain it however it is still a strange concept if not approached right.

  • @Laicicles
    @Laicicles 5 місяців тому +127

    1:40 how can we use addition to define addition? How can that make sense?

    • @aminechakak6460
      @aminechakak6460 3 місяці тому +81

      look up what an inductive proof looks like.
      He's not using addition to define itself, he's using the base case over and over again as a function of counting to define addition.

    • @sibercraft7953
      @sibercraft7953 2 місяці тому +14

      It's as said before an Inductive definition such as for the factorial: if a (different) 0, then a!=(a-1)! x a ,Else (a=0) a!=1. You don't use the operation to define it. You define it by an operation that you already know (multiplication for the factorial,successor for the addition) on the previous term. And by having defined the first term, you have define Ur operation for every terme, since the first term is always reach

    • @tonydai782
      @tonydai782 2 місяці тому +8

      You just repeat applying the definition if it’s not the base case until you get to the base case, where there is no such holdup.

    • @williamhorn363
      @williamhorn363 2 місяці тому +3

      Addition itself is an axiom, so it is not being used to define itself. It is just being defined.

    • @epsilon.sw_
      @epsilon.sw_ 2 місяці тому +6

      We do not define the abstract essence of 'addition', but rather each specific case. Each case makes sense because it is reduced to the basic one, which is defined as true.

  • @tombaron5607
    @tombaron5607 2 місяці тому +12

    Yes but can you prove that 6 was in fact scared of 7?

    • @TheSheep1
      @TheSheep1 13 днів тому

      Yes because he told five “then seven ate nine!”

  • @Peacemaker8D
    @Peacemaker8D 8 місяців тому +19

    Can you explain the set theory behind the definition of addition?

    • @zemm9003
      @zemm9003 2 місяці тому +2

      You can define the successor of a set by adding {set} to it. So you have a set X that represents some number in Arithmetic. The successor will be {X, {X}} where {X} is the only set whose unique member is the set X and X and {X} cannot be equal by the foundation axiom of Set Theory.

  • @VacouslyTrivial
    @VacouslyTrivial 2 місяці тому +2

    This could be generalized by adding the fact that 1+1=2 is e true iff it's belong to ordered ring(if a ≤ b then a + c ≤ b + c.
    if 0 ≤ a and 0 ≤ b then 0 ≤ ab. In fact one can check by replacing usual addition with modulo addition and simply 1+1 mod 2=0 and so the statement is false) and it's multiplicative identity which is 1 and additive identity which is 0 don't coincide i.e 1=0 and 1+1=0+0=0 false otherwise its true and the ring which 0 and 1 belong to it it's trivial

  • @05degrees
    @05degrees 9 місяців тому +27

    I like to define ℕ as an initial semiring, or simpler, when only addition is concerned, as an initial pointed monoid. It really feels more natural than Peano for me. No successor function to talk about.
    Ah I forgot to add. Then 2 is defined as 1 + 1. It really is no less unfair than defining 1 = S0 and 2 = S1.
    What _is_ more interesting to prove based on any definition of ℕ, though, is 2 + 2 = 2 ⋅ 2. In the monoid case, we’ll need to define multiplication to do this, but it’s simple via endomorphisms: like endomorphisms of an abelian group comprise a ring, endomorphisms of an abelian monoid comprise a semiring, which will be that same initial semiring talked about at the start; we only need to show that an initial pointed monoid is abelian first.
    Also we can show the principle of induction from just a monoid definition (all Peano axioms, really; likewise with the initial semiring-initiality is that strong). Cool exercise, won’t spoil.

    • @cloverisfan818
      @cloverisfan818 9 місяців тому

      how did you type the fancy N

    • @05degrees
      @05degrees 9 місяців тому

      @@cloverisfan818 I have a custom AutoHotkey script which replaces strings like \bbN␣ with ℕ but also for many other characters (like \times␣ with × or \A0␣ with Å - my keyboard layout doesn’t have × or Å on its own). Without that, I’d open a character map and searched by name (hoping that I remotely remember how it’s called in Unicode).

    • @vinod-cf2jl
      @vinod-cf2jl 9 місяців тому +1

      ​@@cloverisfan818I think he is using some kind of 3rd party maths keyboard.

    • @PRIYANSH_SUTHAR
      @PRIYANSH_SUTHAR 9 місяців тому

      How did you type black board N in UA-cam comment?

    • @05degrees
      @05degrees 9 місяців тому

      @@cloverisfan818 Sorry, for some reason my comment didn’t post two days ago. I use a custom AutoHotkey script that replaces certain strings with various characters like ℕ, ×, Å, °, «» which I usually first take from the basic Character Map in Windows, but there is a lot of other software for that, including on the web. I won’t post links because sometimes it blocks posting, unfortunately, just search for “unicode character map”.
      Using those by itself might be tedious but I don’t have a good source for advanced keyboard layouts that contain esoteric characters like ℕ, or scripts like mine (mine is a mess, I don’t think it would be useful to anyone except me).

  • @Dinuga2010
    @Dinuga2010 2 місяці тому +2

    Imagine writing this all down while solving a complicated math problem.

  • @vishalmishra3046
    @vishalmishra3046 8 місяців тому +8

    *Counting* is considered more basic or fundamental than addition, just like addition is more fundamental than multiplication and multiplication is more fundamental than power.
    Forward counting is more fundamental than backward counting. Incrementing by 1 is more fundamental and addition can be defined on top of incrementing more than once.
    In a nutshell, 1+1=2 is more fundamental than several assumptions that you have made in the video (which of course are indeed true and can be proved after assuming that some symbol "2" comes next after we define the symbol "1" to be the very first symbol and the start of counting).

    • @odysseas573
      @odysseas573 8 місяців тому +8

      1+1 is not more fundamental than the Peano axioms. It seems that way because it is easier to comprehend and/or because the foundations of math are complicated (at least to most people). But it definitely is not "more fundamental"

    • @__christopher__
      @__christopher__ 8 місяців тому +10

      Counting is exactly what the successor function formalised. The successor of a number is simply the number that comes next. That you can represent the successor by adding 1 is nontrivial and exactly one of the addition axioms.

    • @anotherelvis
      @anotherelvis 3 місяці тому +1

      Some mathematicians prefer to use set theory to define the natural numbers. So that
      0 = {} is the empty set and 1={{}} is the set containing the empty whereas 2={{}, {{}}} and 3={{}, {{}},{{}, {{}}}}
      By that definition sets theory is more fundamental than numbers.

  • @divinecomedian2
    @divinecomedian2 15 днів тому +1

    Terrence Howard is gonna be pissed

  • @kookaburra.boogie
    @kookaburra.boogie 3 місяці тому +2

    This proof is beautiful. Thanks

  • @retrogamingfun4thelife
    @retrogamingfun4thelife 9 місяців тому +9

    if only youtube existed when Russell tried to proof the same thing! ;)

    • @odysseas573
      @odysseas573 8 місяців тому +1

      I am still waiting for a math video on UA-cam titled "The man who ALMOST broke math"

  • @RayTheomo
    @RayTheomo Місяць тому +59

    we got proof that 1+1=2 before gta 6

  • @akialter
    @akialter 2 місяці тому +6

    We invented 1+1=2 to describe one apple and one apple equals two apple. And now we go full circle to prove what we define

    • @chaudhryALIG
      @chaudhryALIG Місяць тому

      That's true, but some mathematical experts disagree with us .

    • @Atlas718
      @Atlas718 18 днів тому +1

      I honestly wonder whats the purpose of it. Why not have numbers as the fundemental building block, as axioms. Its not like we are observing physics or something, its a language, a way to express connections in the real world. Why dedicate so much of our time to proving things we ourselves have defined, by, get this, defining even more stuff.

  • @CatkinsonGD
    @CatkinsonGD Місяць тому

    Was taught growing up to always be skeptical and think critically. Wasnt sure about this one. Had to cover all my bases.

  • @dyjhjfrtt6607
    @dyjhjfrtt6607 12 днів тому +1

    So basically, you have to use addition to prove addition.

    • @adinom687
      @adinom687 11 днів тому

      I mean, not really. He uses the rule “a+b = a when b=0” but I wouldn’t call that addition as much as it’s a formula. It’s like a graph “y =mx+b, m=slope when m and b are constants”. You wouldn’t say that using that formula is taking the derivative even though that’s essentially what you’re doing.

  • @robertlunderwood
    @robertlunderwood 3 місяці тому +11

    It took 379 pages to prove this in Principia Mathematica.

    • @zemm9003
      @zemm9003 2 місяці тому +3

      This is because the concepts weren't well understood. Nowadays it's much simpler. Because we have solid foundations for both Peano Arithmetic and models in Set Theory (so whatever method you choose to prove it with is straightforward).

    • @prototypeinheritance515
      @prototypeinheritance515 2 місяці тому +5

      it didn't take 400 pages to prove 1 + 1 = 2; the authors used that space to establish an entire new foundation of mathematics notation and definitions, and then they just happened to prove 1 + 1 = 2

    • @throughthoroughthought8064
      @throughthoroughthought8064 2 місяці тому +1

      I thought they didn't quite finish it.

  • @zyphre
    @zyphre 2 місяці тому +192

    You define addition with addition?? how is that proof bruh.

    • @Open__56
      @Open__56 2 місяці тому +25

      I'm with you, he makes no sense

    • @miguelf218
      @miguelf218 2 місяці тому +76

      It's a recursive definition. It wouldn't make sense without the base case a+0 = a. If you think about it and look for it on the internet, you'll see that it was a great choice to define things that way since you can prove a lot of things with the induction principle

    • @oop9751
      @oop9751 2 місяці тому +2

      If I give you a iPhone at 7:39 and another iPhone at 7:39 how many iPhones would I have given you?

    • @Gus-s9v
      @Gus-s9v 2 місяці тому +2

      It will eventually go to another definition

    • @TS-cs2pe
      @TS-cs2pe 2 місяці тому +4

      Recursion

  • @rennangandara7697
    @rennangandara7697 Місяць тому +2

    1 + 1 = 2 because the definition of 2 is "the natural successor of the number 1". And the definition of an natural successor is x + 1. So 1+1 equals to 2 because the definition of 2 is litteraly "1+1"

  • @averagenpc1959
    @averagenpc1959 22 дні тому +1

    somehow I always feel like there's a sentence missing in that proof where we have decided that the successor of 1 should be 2, written like that and pronounced as "two". you get what I mean? I feel like it should be mentioned somewhere that the label of the thing was defined as well, and that it is two (2). otherwise, the proof just leads me to 1+1=S(1) and the question of "ya but why is that 2?" is still there.

  • @rcnhsuailsnyfiue2
    @rcnhsuailsnyfiue2 Місяць тому +2

    CGP Beige

  • @Nkzil0501
    @Nkzil0501 9 місяців тому +9

    You are an inspiration sir ✨🙇

  • @CaptainJeoy
    @CaptainJeoy Місяць тому

    The way you ended the video is sorta funny 😅 The way "If you really want to up your math game" just abruptly came in

  • @DanielSouza-zo3qe
    @DanielSouza-zo3qe Місяць тому

    When the student finally figures out what teachers mean by “show work”

  • @yourdailyaveragemat
    @yourdailyaveragemat Місяць тому

    Exam paper: 1a.What is the following calculation euqal to?
    1+1= [1 mark]
    b. Prove why. [6 marks]
    Do not write under this QR code

  • @matthewmitchell3457
    @matthewmitchell3457 Місяць тому

    Imagine if computers defined addition recursively like this. This is why computer scientists and mathematicians get into fights.

  • @Garfield_Minecraft
    @Garfield_Minecraft 2 місяці тому +1

    math just make things up
    this is why I love math👍

  • @mathieutammaro6128
    @mathieutammaro6128 Місяць тому

    Math can sometimes be a convoluted way to express intentions and inuitions.

  • @redder-l8c
    @redder-l8c Місяць тому

    I recommend y all checking out type theory, you can actually implement addition in prog languages like agda

  • @yumcheese2513
    @yumcheese2513 Місяць тому

    thanks bro now i can troll my entire class using this complex equation

  • @uncertainukelele
    @uncertainukelele 5 місяців тому +1

    Terence Howard: hold my beer

  • @fatfurry
    @fatfurry 8 місяців тому +14

    How and why are you using the + in the definition of +? S(a + c) includes a + but it is in the definition of +

    • @fatfurry
      @fatfurry 8 місяців тому +1

      Do you just need recursion?

    • @ViktorLoR_Mainu
      @ViktorLoR_Mainu 8 місяців тому +14

      @@fatfurry Yeah, you use recursion until you have a + S(0)

    • @mcr9822
      @mcr9822 5 місяців тому +3

      @@ViktorLoR_MainuDo you just need recursion?

    • @ianmccurdy1223
      @ianmccurdy1223 2 місяці тому +3

      @@mcr9822 Yes, you use recursion until you have a + S(0)

    • @Random-ly1kg
      @Random-ly1kg 2 місяці тому +3

      ​@@ianmccurdy1223 Do you just need recursion?

  • @ninja4O5
    @ninja4O5 2 місяці тому

    Going to write this in my resume

  • @kenderstone1231
    @kenderstone1231 Місяць тому

    Simple explanation:
    Additions, subtraction, multiplication, and division are created
    Other more complex maths are based on them

  • @joelcraig9803
    @joelcraig9803 5 місяців тому +2

    You know, if you don't pay a university $100.000 dollars, you can just prove 1+1=2 by adding 1+1 together.

  • @Bialanix
    @Bialanix 16 днів тому

    God first learning discreet math and predicate proofs was hell.

  • @bombasticcat
    @bombasticcat Місяць тому

    imagine a universe where 1+1 is a hard problem and people have to study to understand it.

  • @christressler3857
    @christressler3857 5 місяців тому +1

    Now do a video on the proof that 1+1=2 from Russell's and Whitehead's book, Principia Mathematica!😁

  • @SpeedySonicX7
    @SpeedySonicX7 Місяць тому +2

    I’m no mathematician, but I don’t think this is possible. Math is a form of representation. Assigning numbers to things is a uniform way to represent otherwise dissimilar and discrete things with one symbol. If I have a sheet of paper and a cup on my desk, I say there are two things on the desk not because the objects share some material property, but because I choose to represent them abstractly. This eliminates the need for me to be able to perceive a difference in the material objects, so long as I reason that they are indeed not the same object. So if I individually call those objects ‘one,’ I can declare that one ‘one’ and another ‘one’ makes ‘two.’ This verdict of nomenclature isn’t a mathematical law-it’s arbitrary. There’s nothing about the cup that makes it ‘one.’ In other words, the logic that outlines the definition of a number and affirms that 1+1=2 isn’t axiomatic. The validity of the statement is implicitly asserted to make mathematics’ epistemological laws possible, which all ultimately collapse when tasked to explain themselves, much like the paradox of trying to explain language using language.

    • @Veroniquekky
      @Veroniquekky 28 днів тому +1

      Unfortunately, as a person who just graduated from my math major, this is legit. Basically we are showing from the Peano Axioms alone (so only making those core assumptions) we can still prove that 1+1=2.
      Math is just built on an agreed upon set of axioms and everything from there was proved from them including 1+1=2, or that a+b=b+a. Almost everything you can think of as trivial most likely has an equivalent rigorous proof to go along with it.

  • @Glitchrat_YT
    @Glitchrat_YT Місяць тому +2

    Last time i checked, 1+1=3

  • @betaorionis2164
    @betaorionis2164 Місяць тому

    I'm a bit confused with the definition of addition for b0 at 1:35 :
    a + b = S(a + c), with b = S(c)
    Aren't we introducing an addition in the definition of addition? How are we going to know what the successor of (a + c) is, if we haven't yet defined what an addition is?

    • @tlep2979
      @tlep2979 Місяць тому +1

      a + 0 is defined. Since all numbers result from taking repeated successions of 0, a + b_1 is defined recursively as S(a + b_2), where repeated use of the same definition results in a + b = S(S(a + b_3) = S(S(S(a + b_4)))... until at some point b_n is equal to 0, where we switch to our other case a + 0 = a.
      tldr think of it as a recursive function, in pseudo,
      func sum(a, b) {
      if b is 0 -> return a
      else -> return succ(sum(a, pred(b)))
      }

    • @betaorionis2164
      @betaorionis2164 Місяць тому

      @@tlep2979 Yep, the recursive function could be the answer, thx!

    • @Veroniquekky
      @Veroniquekky 28 днів тому +2

      Another way you should look at it is because it’s a definition not a theorem. It’s laying out the rules for addition depending on the value of b and then it uses the Peano Axioms stated before it to give meaning to “a+b”. Seems wack but it’s legit.

  • @matthewsmith2715
    @matthewsmith2715 19 днів тому

    This could be huge

  • @barailmika0702
    @barailmika0702 16 днів тому

    This is typically what happens when I say something simple to my wife.
    She likes to interpret it into something I'll never understand.

  • @Ninja20704
    @Ninja20704 9 місяців тому +7

    For a moment i thought you were going to talk abt the few hundred paged proof but at least this was a little more meaningful to think about.

    • @ZachAttack6089
      @ZachAttack6089 2 місяці тому +1

      This is essentially the same proof. For the one that takes hundreds of pages, most of the pages are used to define the rest of the Peano axioms that were mentioned in the video, so it's not actually hundreds of pages just to do 1 + 1 = 2. For that you only need successor and addition.

    • @Simchen
      @Simchen Місяць тому

      @@ZachAttack6089 The other Peano axioms are just that the successor function is injective and the axiom of induction. How do you need hundreds of pages for that? I think if one really writes hundreds of pages to prove that 1+1 = 2 that's not a proof that's an exercise in obfuscation.

  • @__christopher__
    @__christopher__ 8 місяців тому

    Easy: define 2 to be whatever 1+1 happens to be. This works not only in the natursl numbers but in every algebraic structure that defines both 1 and +. Yes, that includes rings of characteristics 2, for those you just have 2=0.
    Of course for the natural numbers you then have to prove that 2 is the successor of 1.

  • @DoxxTheMathGeek
    @DoxxTheMathGeek 3 місяці тому +2

    I love this proof so much! X3
    Gonna become a preschool teacher to show the kids this thing so they are even more terrified for the next 10 years. :3

  • @BirdMerle-j8r
    @BirdMerle-j8r Місяць тому

    Williamson Crest

  • @oguncanakyol6473
    @oguncanakyol6473 Місяць тому

    Descartes malding rn

  • @noah2123
    @noah2123 Місяць тому

    Oh, so it's like a recursion. If the numbers include something more than one, you have to translate the numbers inside S() with the same rules until you reach a point where 0 is one of the numbers, hence a recursion proof. If you're adding more than one number, you can do two of them and then do another addition.

  • @DeadlockHolmes
    @DeadlockHolmes 8 місяців тому +2

    Yes but why S(1)=2 ? Because S(n)=n+1 ? But why ? And what is n+1 if we use S to define addition. And if u dont use addition, I feel like at the end of the day you use « intuition » (the one we avoided at the beginning) to define what is a Successor

    • @user-tk2jy8xr8b
      @user-tk2jy8xr8b 2 місяці тому

      That's how naturals numbers are defined via Peano axioms. So, 1 is defined as S(0), 2 is defined as S(1)=S(S(0)), 3 is defined as S(2), and so on. S is not "plus one", it's "next", so 0 is the first, 1 is next, then goes 2 etc. There is no intrinsic addition or multiplication, just a sequence of things. You can define an addition over them, the video shows you how. You can also define multiplication: a * 0 = 0; a * S(b) = a + (a * b). Funny enough, you don't even have equality out of the box. Let's define it: 0 == 0 = True; S(a) == S(b) = a == b; _ == _ = False

    • @daniiltonkonog186
      @daniiltonkonog186 2 місяці тому +1

      S(1)=2 because 2 is just a symbol that means nothing . I mean we can define set of natural numbers as N = {0, S(0), S(S(0)), S(S(S(0))), and so on …}. Numbers are just a symbols.

    • @user-tk2jy8xr8b
      @user-tk2jy8xr8b 2 місяці тому

      @@daniiltonkonog186 right, we can also talk about bijections between {Z,S(Z),S(S(Z)),S(S(S(Z))), ...}, {0,1,2,3,...}, {zero,one,two,three,...}, and other sets that enumerate natural numbers

  • @flantc
    @flantc Місяць тому

    Real analysis flashbacks!

  • @theencryptedpartition4633
    @theencryptedpartition4633 9 місяців тому +2

    This is some terrance Howard level stuff

  • @wing_103
    @wing_103 2 місяці тому +1

    o (1 circle) + o (1 circle) = o o (2 circles)
    Edit: In hindsight, this is technically visual proof and is not reliable for calculations.

    • @Veroniquekky
      @Veroniquekky 28 днів тому +1

      The main issue here is it’s not based on any agreed upon fact. You’re essentially stating that 1+1=2 as an axiom (something we assume to be true). Versus the video went one step deeper only assuming the Peano Axioms stated and the Addition definition using the Peano Axioms to then prove 1+1=2. Kinda wack but technically to a math major it is different. This was probably a shit explanation, sorry lol

  • @MrBerryK
    @MrBerryK 2 місяці тому

    Now prove that addition is commutative!

  • @decract
    @decract Місяць тому +6

    1:34 even the definition of addition has addition

    • @Veroniquekky
      @Veroniquekky 28 днів тому +2

      Because it’s a definition… not a theorem. It’s laying out the rules for addition depending on the value of b using the Peano Axioms stated before it. Seems wack but it’s legit.

  • @pokalukawan
    @pokalukawan 9 місяців тому +3

    you haven't shown that n = m implies S(n) = S(m) which you use when you say S(1+0)=S(1). You also haven't shown why 1≠0. you could use 1=S(0) and S(n)≠n but that hasn't been shown either

    • @prototypeinheritance515
      @prototypeinheritance515 9 місяців тому +3

      S(n) is a function which is by definition right-definite; that is the property you're looking for.
      The second claim can't be proven from the axioms given in the video. The peano axioms have a statement for this: "zero isn't the successor of any number" or in first order logic, forall n: Nat, S(n) ≠ 0.

  • @briantenneson6812
    @briantenneson6812 6 місяців тому

    Well it’s not just 1+1. You also need to prove that for the set of natural numbers, addition and multiplication are distributive, associative, and commutative. A proof of just 1+1=2 is just one line long but proving that multiplication is associative is a bit more challenging. Do you know how to prove multiplication is associative and together with addition being distributive? It’s kinda fun.

  • @shaunmahlangu1673
    @shaunmahlangu1673 Місяць тому

    Ngl, I clocked out after the 2 stars.

  • @studio48nl
    @studio48nl Місяць тому +1

    I'm not a mathematician, but you use an addition in the proof of adding?! S(1+0). Is that valid?

  • @JustifiedNonetheless
    @JustifiedNonetheless 2 місяці тому +1

    Prove "1" = "one" and that "2" = "two."
    For that matter, prove "1" or "one" = the concept to what they refer. You can't. These things are only true because we stipulated them as such. We could just as easily have stilulated the numeral "1" to correspond to the word "eight," and for both of those to correspond to the idea of 962.

    • @pawn_b4
      @pawn_b4 Місяць тому

      The whole assumption of the video is that we have already defined the sequence of natural numbers. You are completely correct in that we have *defined* that 2 is the successor of 1, and that is completely arbitrary. It could have been 3, or 4, or X, or any other scribble. But that's not the point of the video. We assume that 2 is the successor of 1, and prove that 1 + 1 = 2. More precisely, we define the semantics of the addition operator using inductive reasoning, and then apply it to the case where the left- and right hand side of the addition operator are 1, which turns out to be 2, which in turn proves 1 + 1 = 2.
      Proving without definitions is impossible. Otherwise, what are you proving? It could be anything.

  • @greatguytv
    @greatguytv Місяць тому

    This looks like something b russel would try and failed

  • @friedoompa-loompa2876
    @friedoompa-loompa2876 Місяць тому

    When a simple equation is solved with algebra

  • @KingSlayer21_0
    @KingSlayer21_0 Місяць тому

    That one friend on a Tuesday afternoon :

  • @Ballpitmaster
    @Ballpitmaster 11 днів тому

    My brain is on fire, I thought 1+1=11

  • @GD_MiT
    @GD_MiT 9 днів тому +1

    i thought it will be like
    1+1 = 2
    1+1-2=0
    2-2=0
    0=0

  • @Ryan-fq9dj
    @Ryan-fq9dj 2 місяці тому +1

    I need proof that this proof is legitimate before coming to the conclusion that 1+1=2

  • @XPlays_24
    @XPlays_24 3 місяці тому +1

    The equation 1 + 1 = 2 is one of the most basic concepts in mathematics. It’s based on the idea that the number "1" represents a single unit or object. When you add another "1" to it, you’re combining two separate units. This combination gives you "2," which represents two units together.
    Mathematically, this can be explained using the Peano axioms, which are basic rules that define how numbers work. These rules tell us that if you have 1 and you add 1 more, the result is the next number, which is 2.
    This idea is not just about counting; it’s fundamental to all of mathematics. Whether you’re adding numbers in a simple equation or using math in complex science and technology, the concept that 1 + 1 = 2 is a building block that everything else relies on.
    In essence, 1 + 1 = 2 is true because of how we define and understand numbers, and it’s a principle that applies universally, no matter what you’re counting or calculating.

  • @zuraforreg3088
    @zuraforreg3088 3 місяці тому +3

    If you question 1 + 1, then you should question a + b, i.e. the `plus` operator itself. It means that `plus` is not defined and you are trying to define it, but at the same time you are using `plus` freely (as if already defined) in arguments for S... e.g. S(a+c). You are not allowed to use it since `+` is not defined.

  • @jjthetrainman9430
    @jjthetrainman9430 8 днів тому

    I generally just say proof by definition since that's our definition of two

  • @lirantwina923
    @lirantwina923 9 місяців тому +1

    Please try to integrate 1/x^5+1

  • @wildfire_
    @wildfire_ Місяць тому

    I think it’s more accurate to say that 2 is 1+1. 2 is, by definition, the number that comes immediately after 1, and is thus the successor of 1 (which is 1 + 1)

  • @calebmurugan6327
    @calebmurugan6327 Місяць тому

    question: if b=1 is the successor of 0 then wouldn't a=1 also be a successor of 0 the the equivalence of a+b would be S(0+0) which is 1. please help to explain

  • @imshiruba
    @imshiruba 8 місяців тому

    me: 1/2 + 1/2 is 1 because 1+1=2... wait, is it really 2? I gotta check the proof

  • @kamisek762
    @kamisek762 13 днів тому +2

    tho what is use for that? i mean why do you need proof off 1+1?

  • @Gordy-io8sb
    @Gordy-io8sb 6 місяців тому

    What about fields? 1+1 = 0 in a field of characteristic 2, or, 1+1 = 0 (mod 2).

  • @CheaddakerT.Snodgrass
    @CheaddakerT.Snodgrass 9 місяців тому +3

    Interesting. Would you agree that the three cardinal, trapezoidal formations, hereto made orientable in our diagram by connecting the various points, HIGK, PEGQ and LMNO, creating our geometric configurations, which have no properties, but with location are equal to the described triangle CAB quintuplicated. Therefore, it is also the five triangles composing the aforementioned NIGH each are equal to the triangle CAB in this geometric concept?

  • @mowzaw
    @mowzaw 5 місяців тому +2

    1️+1️=11

  • @GDhatenal
    @GDhatenal Місяць тому

    Use a numberline and get two ones they take up area one when "added together" (one put in front of the other) they take up an area of 2 so 1+1 must be 2

  • @Mono_Autophobic
    @Mono_Autophobic 2 місяці тому +1

    2 is just a symbol to represent what 1+1 will be
    We can call it anything

    • @chaudhryALIG
      @chaudhryALIG Місяць тому

      Yes that's the truth but so called mathematical experts and genius believes that 1+1 can be proven mathematically .

  • @god5535
    @god5535 6 днів тому

    1+1=2 because it is DEFINED that way.

  • @AidanDaGreat
    @AidanDaGreat 2 місяці тому +2

    99k people:
    *Interesting.*

  • @emre_ez
    @emre_ez 2 місяці тому

    A book called Principia Mathematica has 360 pages of theorems to get to 1+1=2

  • @TopRob1
    @TopRob1 9 місяців тому +3

    I'm not sure if S(1+0) is equal to S(1), I need proof

    • @darthnihilus9342
      @darthnihilus9342 9 місяців тому +2

      He showed that, by definition, a+0 = a

    • @GabriTell
      @GabriTell 9 місяців тому +2

      We know by definition that "x+0=x" for an arbitrary "x".
      So, we have that "1+0=1" is true, and by definition of "=" we have that given an arbitrary property "φ", then "φ[1+0] φ[1]" is tautology.
      So, particularizing "φ[x]" as "1+1=S(x)" for an arbitrary "x", as he's already proven in the video that "φ[1+0]" is true, by modus ponens we have "φ[1]" is true, and therefore "1+1=S(1)" is true.
      So, by transitivity and symmetry law, we have: "x=y" and "y=z" implies "x=z", and "x=y" implies "y=x" for "x", "y" and "z" arbitrary. Therefore, as we have "1+1=S(1+0)" implies "S(1+0)=1+1" and "1+1=S(1)" is true (as we've already proven), we conclude that "S(1+0)=S(1)". □

    • @ssaamil
      @ssaamil 9 місяців тому

      ​@@GabriTellNicely done!

    • @samueljehanno
      @samueljehanno 8 місяців тому

      ​@@GabriTellNicely done

    • @user-tk2jy8xr8b
      @user-tk2jy8xr8b 2 місяці тому

      Easy, S(S(0)+0) =[congruence of a+0=a over S]=> S(S(0))

  • @nicholi8208
    @nicholi8208 5 місяців тому

    Terrance Howard : hold my crack pipe