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Mathe-News! 🚨 Die Jacobi-Vermutung wurde mit einem Tweet widerlegt!

16:21EnglishTranscribed Jul 23, 2026
0:00

There's more sensational news

0:02

from the world of mathematics, because, hey everyone,

0:05

by the way, the Jacobi conjecture is

0:06

wrong. Levent just

0:08

casually writes on X, formerly Twitter. He thanks

0:11

his friend who asked around

0:12

and his second good friend

0:13

Fable, the AI ​​model from

0:15

Anthropic, which he started up.

0:17

And that provided a counterexample to the

0:19

Jacobi hypothesis. Everyone can now

0:21

calculate and verify this for themselves

0:22

. Indeed, this is a

0:25

counterexample and this is

0:26

incredible news, because this Jacobi

0:28

conjecture has been a part of mathematics for

0:30

decades now. It was a

0:32

highly renowned, unsolved problem,

0:34

and apparently there is a rather

0:36

basic counterexample that

0:38

no one has noticed yet. What's going on there?

0:44

In this video, we'll take a closer look at the mathematics behind it, the history, and what's going on right now.

0:46

As early as 1939, Heinrich Keller

0:49

suggested that if one

0:54

has a polynomial function from the immense space to the immense space and

0:57

its codomain matrix

1:00

is ​​constantly non-zero in the determinant, then

1:03

an inverse mapping also

1:04

exists as a polynomial function. So, I'll just

1:07

put it simply using

1:08

complex vector spaces and complex

1:10

numbers. One could

1:11

take any body with characteristic zero here.

1:13

You can also think about real numbers.

1:15

And if we now

1:16

map from the nimensional space here, it means that there

1:18

are, so to speak, n variables on which

1:20

everything depends, and that we are mapping into the

1:22

nimensional vector space

1:24

. This means we have, so to speak, n

1:26

different coordinate components, which are

1:28

all individual functions that

1:30

depend on the variables.

1:33

In the case of n = 2, one could

1:35

imagine that there are two variables x and

1:36

Y, and that a vector with

1:39

two components always results as an image

1:40

, which depends on x and Y,

1:42

and that the whole thing should be a

1:44

polynomial function

1:46

, meaning that one is only allowed to

1:48

add, subtract, and multiply.

1:50

Division by is not even allowed; this function can only be formed using plus,

1:52

minus, and multiplication

1:53

, then it is a

1:55

polynomial function. And with the Jacobi

1:57

matrix, one considers, so to speak, the

1:59

derivation from this construct. The

2:01

problem is, if you

2:03

know derivatives from school, then when I

2:05

look at the slope of a

2:06

function that has one variable,

2:08

we now have a problem. We have

2:09

several functions and

2:11

several variables, and therefore, in a

2:14

table, we get a whole

2:16

matrix where I go through each individual function in each row

2:18

and differentiate in each

2:20

column with respect to each individual

2:22

variable. So in our

2:24

example, we can

2:25

calculate all of this using the individual

2:26

derivatives. And if you now look at the

2:28

determinant, you are essentially looking at

2:29

how the volume changes at

2:33

this one point where we

2:34

made the derivative, if

2:36

I evaluate the mapping once at this

2:38

point and/or around this

2:40

point. And then,

2:42

locally, it becomes clear how the

2:44

volume will be affected, whether it will be increased or

2:46

decreased. And as long as that

2:47

is not zero, as long as the volume is

2:49

not shrunk to zero,

2:50

I can at least reverse it locally at this point

2:52

. And

2:54

the assumption is that if this

2:56

shrinking to zero doesn't

2:58

happen everywhere, and even if

2:59

this change in

3:02

volume is constant everywhere, and

3:04

only the directions

3:06

change slightly, then I can also

3:08

invert it again, even polynomially

3:09

. So in our example, if we

3:11

calculate it concretely, inverting also means that

3:13

we can

3:16

rearrange the entire system of equations for X and Y, and we get nice polynomial expressions for U and V again

3:18

, only

3:21

with plus, minus and multiplication.

3:23

However, if we modify the example just a little

3:25

and then

3:27

look at the Jacobian matrix determinant again, it

3:30

now depends on X and is

3:32

no longer non-zero everywhere. And

3:34

while we might still have

3:36

a way to rearrange it for U and V, we'll

3:38

no longer have

3:39

neat polynomials. And the Jacobi

3:41

conjecture is precisely that as long as

3:43

we somehow construct a system of equations

3:45

where the

3:47

corresponding Jacobi matrix is ​​constant and equal to

3:50

zero, we will

3:51

always find nice polynomials to invert

3:53

. This was first written down

3:56

as a conjecture in specialist literature in 1939

3:58

. And because the

3:59

statements here are relatively easy to understand

4:01

, there were many

4:03

attempts to prove them, although these occasionally

4:05

contained errors. And that thing

4:07

was still an open, unresolved

4:09

problem, and also a very well-known one. When it became

4:11

clear in 1998 that a new

4:14

century was about to begin, people

4:15

remembered how Hilbert had presented around

4:17

23 famous problems, or

4:20

problems that had since become famous, in 1900

4:22

. And then

4:23

a Fizz Medal winner also

4:25

addressed this question: what are

4:27

the problems for the next century?

4:29

Several Millennium Problems

4:31

and questions that remain unresolved to this day emerged.

4:33

Among other things, I believe it was also number 16,

4:35

the Jakobi

4:36

assumption. So, what I mean to say is that this

4:38

problem has actually been

4:40

noticed and addressed by the mathematical world.

4:42

Many have tried it. There were

4:44

also some pieces of evidence that

4:46

were presented, but they always

4:47

contained errors. And a particularly

4:49

tragic case is Yitang Sang,

4:51

who addressed this in his doctoral thesis

4:53

and was even

4:57

able to prove something more general. However, he had used a Lemmer

5:00

from his doctoral advisor, which turned out to be

5:03

incorrect, and therefore

5:05

all his proofs failed. And

5:07

then, although he was on a

5:08

pretty good path, he simply couldn't

5:10

get a position anymore because, to put it bluntly, people said

5:11

he was just talking nonsense

5:13

in his desert and that's why

5:15

he was kicked out of the academic

5:16

world, so to speak,

5:19

but he had a great comeback

5:21

because he was the first to show

5:22

that there are infinitely many

5:24

prime numbers that have a finite,

5:26

predetermined distance between them.

5:28

And the Akobi conjecture was also

5:30

notorious in that there were some

5:31

conjectures where one already knew that

5:33

these were still generalized things.

5:35

If any of them are true,

5:37

then they each imply the

5:39

Jacobi hypothesis. So the Jacobi

5:40

conjecture was already central in many

5:42

places in algebrean geometry,

5:44

and it also appeared somewhere else

5:46

. In 2005, it even became

5:49

clear that the Jakobi conjecture

5:50

is equivalent to the Dixm conjecture, where

5:52

such a physical connection

5:54

could even be established. And

5:56

then Levent just comes along, throws out

5:58

a tweet like this, all in

6:01

lowercase and so casual.

6:03

Yes, I had some calculations done here while the World Cup final was on

6:04

. The AI

6:06

told me something. Here is the result, by the way

6:07

. Do whatever you want

6:09

with it. Yes, and the crazy thing is, you

6:11

can simply do the math now. We

6:12

have specified the function here with

6:14

three variables X, Y and Z. The

6:16

three components are also present. So

6:18

now we can set up the entire

6:20

Jacobi matrix. I

6:22

tried it once. This is going to be

6:23

a rather lengthy bill.

6:25

Then you would have to

6:26

calculate the determinant. However, you can

6:27

also have the computer

6:29

calculate this perfectly. So Wolfram Alpha

6:31

can do that. Levent even provided a

6:32

direct link to

6:34

Wolfram Alpha in the very next subtweet, where you

6:35

can calculate it and see, aha,

6:37

the determinant is indeed -2,

6:40

not 0, and that's independent of the

6:42

values ​​of X, Yy, and Z.

6:44

Everything cancels out here, and in the end, you

6:46

really do get the constant -2. The

6:48

requirements are met, but

6:49

three points can still be found.

6:52

Two would have been enough; find three points

6:54

that all have the same

6:55

function value, that are mapped to the

6:57

same point, and

6:59

therefore it is

7:00

no longer possible to invert back from this point. And the

7:03

function is not injective, the

7:04

function is not invertible,

7:07

so in particular it does not have a nice

7:08

polynomial inverse. It is simply

7:10

not invertible at all and therefore

7:11

a crystal-clear, flawless

7:14

counterexample to the Jacobi conjecture.

7:17

Wow, from here on things really picked up

7:20

speed. The news spread

7:22

not only via X or Twitter,

7:24

but also directly

7:26

reached Wikipedia, where someone

7:27

had written directly. Incidentally,

7:29

a counterexample has apparently been

7:31

found here. Then, of course, other

7:32

Wikipedia authors said that just because

7:34

some guy on Twitter said he had something to say,

7:36

we can't just

7:37

change the Wikipedia article now.

7:39

Everyone said: "Yes, guys, you

7:40

just have to do the math, this is a

7:42

counterexample that works." He

7:44

even

7:45

provided links himself where the calculations are done. You

7:47

can calculate it yourself. My

7:48

other one, no, that doesn't count as a source;

7:50

a reputable source has to do that first

7:51

. But that's the beauty of

7:53

mathematics. Anyone can

7:55

calculate it. It works. And

7:57

Levent, by the way, isn't just

7:59

anyone who casually

8:01

ran the thing on the side and

8:02

discovered something he

8:04

wouldn't understand himself. Firstly, he is currently

8:06

employed by Anthropic. That

8:08

's perhaps also very important to

8:09

say. So, as an employee of Anthropic, he was able to use Fable, the best AI

8:12

model from

8:14

Anthropic,

8:15

and therefore certainly didn't have as many

8:18

limitations as some others

8:20

who try to get the maximum out of their paid version

8:24

. Especially since

8:26

Enphropic goes to great lengths to ensure that

8:28

Fable cannot be used for any

8:30

bad things and

8:31

therefore prefers to use weaker models

8:33

if you

8:37

want to do something with it, even partially during programming. And Levent

8:39

also has a top-level mathematical education.

8:41

He was a postdog at Harvard.

8:43

One also sees Princeton and Cambridge mentioned

8:44

in his CV, and his doctorate.

8:46

Father Manjul Bagava is himself a

8:48

polystyrene carrier.

8:51

It doesn't get more prestigious than that in mathematics, and

8:52

even his bachelor's supervisor Jacob

8:54

Zimmermann is not yet a

8:56

medalist, but that could

8:59

change this Thursday afternoon, German time. The

9:01

International Congress of

9:02

Mathematicians begins in Philadelphia this year, and

9:04

Jacob Zimmermann will very

9:05

likely receive a field medal there

9:07

. The Fiels medalists were

9:09

apparently already accidentally

9:10

awarded a Fiels medal, and therefore it is actually

9:11

clear that Jacob Zimmermann will also

9:13

receive a Fiels medal, and he was,

9:14

as mentioned, the supervisor of

9:16

Levent's bachelor's thesis. So he was very well

9:18

connected in mathematical circles

9:20

and definitely knows something about

9:22

mathematics. So perhaps

9:24

, in order to truly see new results at the top

9:28

, we also need people who ask the right

9:29

questions to AI and who know

9:31

what is currently possible. And who knows what other

9:35

clever hints were hidden in his prompting,

9:36

or what other directions he

9:38

tried out with Febel and the AI ​​here

9:40

. Unfortunately, he only shared the result

9:42

and not

9:44

the process leading up to it. That's a bit of a

9:46

shame, in a way.

9:47

But this isn't really a major

9:49

academic publication he's

9:50

made; he simply wanted to

9:53

share this result with the world quickly. Of course, there could also be a

9:54

lot of strategic planning and marketing by the company

9:56

behind it. We don't know any of that right now

9:58

. But even if

10:00

the AI ​​gives you such a result

10:02

, there's still a bit of a

10:03

problem: you might not be able to understand the reasoning behind the AI's

10:06

Chain of Thor

10:07

and

10:09

read its thought process. But the AI

10:11

itself also consistently labels its sources as

10:13

bad. This is generally a

10:14

problem with the latest

10:16

developments in mathematics. And these

10:18

two problems are precisely the

10:20

question now: where does this actually come from? So, firstly,

10:23

how did the AI ​​get there in its

10:24

thought process, and

10:25

secondly, what kind of data

10:28

might be contained in the AI's training data

10:29

that led it to this point, where

10:31

even the AI ​​itself cannot say exactly

10:33

where it comes from. Well, at least

10:35

for the first time, how might one get there

10:37

somehow?

10:39

Chat GPT seems to have

10:41

provided a fairly convincing answer, where

10:43

a result can be achieved without having to

10:48

pull a function out of thin air, using three

10:49

variables and a few combinations of them

10:51

, but rather by

10:54

mentioning other abstract objects. I myself

10:56

no longer understand what's going on at this

10:57

Algebrach level. But

10:59

at least here Daniel L said, ah, that

11:02

really seems to work. And

11:04

that's a plausible argument, which

11:06

other Twitter users have also suggested is about on

11:08

the level of something that could become

11:10

a university exercise

11:12

. So, there seem to be some

11:13

abstract arguments about how to get there

11:14

. And what I

11:16

find very interesting is that the example

11:18

constructed here seems to be

11:20

based on another example, which is somehow contained in

11:22

a Russian article that only

11:24

cites its own source,

11:26

which I found through a translated

11:27

Chinese tweet—so some

11:29

obscure math paper from

11:31

1999. Jakobi is mentioned directly in the title

11:34

. I can still

11:36

read enough Kürillig to see that Jakobi somehow

11:38

appears here. And as example 1 in

11:40

this paper, in this five-page

11:42

paper on page 4,

11:43

a function with two

11:45

variables actually appears, and then also

11:47

both components, i.e., of R² R²

11:49

or c² c², where the

11:52

determinant of the Jacobian matrix

11:57

is ​​actually -2 constant, independent of x and y. And this example

11:59

wasn't explicitly

12:00

mentioned again, that there are two points

12:01

that map to the same one, but

12:03

you can actually find them in this

12:04

example here as well. This is at least also

12:08

given here as an example of an irreversible mapping. And this

12:10

example has, so to speak, only one

12:12

problem: dividing

12:13

by y is calculated at one point,

12:15

and therefore it is not a polynomial. All you were allowed to do was

12:17

add, subtract, and

12:19

multiply. And if one could, so to speak, find out this

12:21

division by here,

12:22

one would also have a counterexample to the

12:24

Jacobi conjecture. And that's exactly what happens

12:26

when you introduce such a clever

12:27

third component, add a third

12:29

variable; then you

12:30

somehow manage to

12:32

multiply out this division and

12:34

actually get the example that

12:37

Fable seems to have

12:39

arrived at somehow, perhaps via this

12:41

obscure Russian paper—we do

12:43

n't know, and that's the problem:

12:44

the AI ​​doesn't know anymore whether it

12:47

used this specific Russian paper, where perhaps a

12:49

scientist, a mathematician, if they

12:50

had read it and

12:52

come up with the idea based on it

12:53

, would have cited it as a source. Well

12:56

, as I said, that's a whole topic in

12:57

itself, how AI should perhaps also

13:00

use sources and reference them again

13:02

when it uses ideas from them. Well

13:04

, we've added this third

13:05

variable, and now we

13:07

actually have a counterexample for the case n = 3,

13:10

and I could also

13:13

simply add a fourth, fifth, or sixth variable here as a dummy variable

13:14

. This is, so to speak, a

13:16

counterexample, which shows that for all n

13:18

greater than 3, the Jacobi conjecture is

13:21

false. For n = 1, it is

13:24

quite clear, because then this

13:26

matrix is ​​just a 1 x 1 matrix containing the

13:29

derivative itself. And if

13:30

the derivative is constantly non-zero, that

13:32

means I have as a function

13:34

only a straight line that has a slope

13:37

non-zero and

13:38

is therefore invertible everywhere as a

13:40

second straight line. So the case n = 1 has

13:42

always been clear, and the case nö

13:45

= 3 has now been disproven.

13:47

However, what remains open is the

13:49

case n = 2, and in a certain sense,

13:51

this is actually the most interesting

13:53

case. This is perhaps also called the

13:56

planar or

13:58

planar Jacobi Conjecture. And it is

14:01

historically quite interesting that only

14:02

last year, when a

14:04

comprehensive research was undertaken, it was

14:05

discovered that there is a paper from 1884 that has been

14:09

virtually ignored since then, in

14:10

which the Jacobi conjecture was actually formulated for the case

14:13

n= 2

14:16

. So historically,

14:18

the

14:20

only remaining case n= 2, which

14:23

was first mentioned, is

14:25

quite an interesting problem; it

14:26

should actually be the case. I believe

14:28

the 1884 paper even contains a kind of

14:30

proof of this, but it

14:31

contains an error. So, this pattern of

14:35

false evidence has been a recurring theme throughout the history of the Jacobi hypothesis.

14:37

However, for the case n = 2,

14:39

such a simple polynomial is not possible, since

14:42

the degree of Leven's polynomial

14:44

is only degree 7 compared to its opposite. This does

14:48

not work in the case with two variables. They've already

14:49

calculated everything up to over 100 degrees and

14:52

seen that it can't work.

14:53

So, if there were a counterexample

14:55

, it would have to be of at least degree

14:57

100. And in a certain sense,

14:59

the Jacobi

15:01

conjecture has not yet been definitively

15:03

defused. The really exciting

15:04

problem now is the case with

15:06

two-dimensional vector spaces 2, but

15:10

the general Jacobi conjecture, which was

15:12

often also implied by

15:14

other theorems, has now

15:15

actually been refuted for the case three and

15:18

larger. And that also means

15:20

that every theorem—and there is a whole

15:22

list of them—that the general Jacobian

15:24

conjecture would have implied is also false in

15:26

its generality in this form

15:28

. And so to speak, for all these

15:30

assumptions here there is at least one

15:32

dimension, a finite dimension, in which

15:34

the original assumption, as

15:36

formulated here,

15:38

can simply be refuted. And that, based on everything

15:40

I gathered yesterday

15:42

and have read a bit more about today

15:44

, is the current state of affairs in

15:46

mathematics. There's this big

15:48

bombshell announcement, and now you're fully

15:50

informed about what it all means.

15:51

At least I hope you enjoyed the fact

15:53

that I took a look at all of this

15:55

and have

15:56

now prepared it for you here. This shows

15:58

that sometimes open assumptions

16:00

remain open precisely because they

16:02

are also false statements, such as

16:04

the assumption about the bunk bed. And on

16:06

Thursday, not only Levenz's

16:07

Bachelor supervisor will probably receive a

16:09

Feds medal, but also Hong Wang,

16:10

who proved the Kakea suspicion.

16:13

I also made a Matte News video about that

16:14

. There's a lot going on

16:16

in mathematics.

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