Channel
@MathfromKrach
On this record: Growth · Engagement · What this channel posts · Posts · Citations · Cite this entry
149subscribers
+0 since we began measuring on 6 August 2026
Risers and fallers across the register · movement among entries of Under 1,000.
| Telegram ID | -1001423845180 |
|---|---|
| Type | Channel |
| Username | @MathfromKrach |
| Description | Hey, I’m Dmitry Krachun (@dmitrykrachun), currently a postdoc at Princeton, department of mathematics. I mostly post about research level maths that I stumble upon. |
| Created | Between 1 April 2019 and 31 August 2021— estimated from Telegram’s id allocation, not measured. How this range is calculated. |
| First recorded | 8 August 2026 |
| Last confirmed live | 8 August 2026 |
| Measurements held | 2 |
| On Telegram | t.me/MathfromKrach |
| Measured (UTC) | Subscribers | Change |
|---|---|---|
| 8 Aug 2026, 20:15 | 149 | no change |
| 6 Aug 2026, 08:21 | 149 | first reading |
20 posts held, back to 28 February 2025 — the reader has not yet reached the start of this channel’s public history, so older posts may sit further back, unread. Read across 1 pageof Telegram’s post history, 20 posts per page.
ERR is average views per post over the last 30 days divided by subscribers, the definition TGStat uses, so this figure is comparable with the one you will see elsewhere. It falls structurally as a channel grows: a high ERR on a small channel and a low one on a large channel describe reach mathematics, not quality. We publish the figure and the sample it came from and pass no verdict on it.
ER is defined industry-wide as (forwards + reactions + comments) ÷ views— note the denominator is views, not subscribers. Telegram’s public web preview carries views and reactions but not forward or comment counts, so the reaction rate above is the reactions term only and is therefore a floor: the true ER for this channel is higher by an amount we have not measured and will not estimate.
| Window | Rolling 30 days · latest post in window 4 August 2026 |
|---|---|
| Posts held | 20 (28 February 2025 – 4 August 2026) |
| Views total | 124 |
| Reactions total | — |
| Forwards / comments | not exposed by the public surface — not measured, not estimated |
| Readings taken | 8 Aug 2026, 20:15 UTC |
Views are a single reading per post, taken at the time above. A post published in the last day or two is still accumulating views, which pulls the 30-day average down slightly. That is a property of the standard definition rather than a fault in it, so we keep the definition rather than “correcting” the number into something nobody can reproduce.
Precision. Telegram publishes view counts on its public widget in short form — 8.12K, 3.7M — so any reading at or above 1,000 reaches us rounded to three significant figures, and only counts below 1,000 are exact. Averages and rates derived from them are shown to the same precision rather than to the unit: a figure like 3,701,250 would assert digits nobody measured.
Reaction counts are published per emoji and rounded the same way, so a total below 1,000 is exact and a larger one is a sum that may carry a rounded component from each emoji above 1,000. Because it is a sum, it does not look rounded — read a large reaction total as three significant figures per contributing emoji rather than as the figure it prints.
Lifetime counters from Telegram’s own channel header, read 8 August 2026 — not the date at the top of this page, which is when the subscriber count was last read. Below Telegram’s rounding threshold, so these counts are exact.
Turns out, for the square-difference-free sets one can do better than Ruzsa's approach! The paper is inspired by several recent AI-generated (counter)-examples based on smart combination of several prime moduli. The new approach doesn't get anywhere close to n^{1-eps} and I tend to believe that a universal bound n^{1-c} for some absolute constant c>0 holds. The paper is now also on arxiv: https://arxiv.org/abs/2608…
Multiplication table, more than you wanted to know!
Denote by s(n) the size of the largest subset of {1, 2, ..., n} not containing two distinct elements differing by a square. Strangely, back when I was writing the quoted post, as far as I can remember, the best upper bound I knew was of the form N*(\log N)^{-c\log\log\log N}, which is better than "classical" bounds for the 3-AP problem, i.e. the problem of estimating the size of the largest subset of {1, 2, ..., n} w…
Let A be a triangle. Suppose points of a circle are coloured in two colours, is it always possible to find a monochromatic triangle similar to A? Turns out, that the answer is yes if and only if A has angles (pi/7, 2pi/7, 4pi/7). More generally, Stromquist conjectures that for any two-colouring of a circle with unit circumference, one can find a monochromatic d-gon with arc-length equal to 1/(2^k-1), 2/(2^k-1), \dot…
Looking again at the article about the Lonely Runner Conjecture for 8 runners [2], I noticed that the author also proves an improved version of the statement "if the set of speeds forms a lacunary (enough) sequence then there exists a time when the runner whose speed is set to zero is lonely". Lacunary sequence in general means that v_{j+1}/v_j>1+\eps for some \eps>0 and all j, and in this particular setting \eps is …
Problem 2: This is a problem from Erdös. Let n_k be a lacunary sequence of positive integers, i.e., n_{k+1} > (1 + \eps)*n_k for some \eps>0. Can we find a real \theta such that all distances from n_k*\theta to the nearest integer are separated from 0 (exceed some positive \delta for all k)? This question has been answered positively, the bound for \delta in terms of \eps has been improving over time with the best k…
Proceeding further following the transcript we see that Alice, Bob, and Charlie must also identify (x+d, y+d, N-x-y-d) as a YES instance, leading to a contradiction! Now, what can be said about an upper bound for the size of a set avoiding corners and hence a lower bound for the number of colours needed which implies a lower bound on the communication complexity? Even the bound of o(N^2), which translates into super…
Here is a surprising neat connection between communication complexity and additive combinatorics. Communication complexity problem: suppose Alice, Bob, and Charlie each have a number written on their hat: a, b, c, all three from 1 to N; so that each knowns the other two numbers. Sending bits of information between each other, they want to decide whether a+b+c=N. How many bits do they need to send? Trivially, having…
Here is a proof: suppose some stopping time S achieves very small distance to the stationary. Let’s run additional Uniform(1..T) steps on top of S steps. The measure of the end point is still very close to stationary since running a fixed number of steps from the stationary measure still gives you a stationary measure. Now, we claim that the end point after S+Uniform(1…T) steps can be coupled with the end point after…
Here is one interesting fact. When you have a Markov chain (think of a random walk on a finite graph) an important quantity to look at is mixing time: How many steps does one need to take so that the distribution becomes close to the stationary distribution of the Markov chain? One instance of this problem is: How many shuffles are required to mix a deck of card? There are several ways to measure closeness but peop…
At the end, let me mention that I believe lonely runner conjecture to be wrong with a huge margin. Taking a random time it's easy to see that a gap of 1/(2k) always exists and I believe that for large k, even the bound of 1/(1.99*k) is wrong. See also this post [3] of Tao where he explains how to improve 1/(2k) by something of the order of log{k}/k^2. [1] https://www.arxiv.org/pdf/2509.14111 [2] https://terrytao.wor…
Anyone interested in improving the state-of-the-art result for the lonely runner conjecture? Lonely runner conjecture states that if k+1 runners start a race running on a circle of unit length with distinct speeds v_1, v_2, ..., v_{k+1} then for each index i there exists time t such that at time t the i-th runner is at least 1/(k+1) far away from all other runners. By substracting the speed of the i-th runner this c…
Showing the 12 most recent of 20 posts we hold for @MathfromKrach. View and reaction counts are the latest single reading for each post, not a live figure, and a recent post is still accumulating both. A view count marked ≈ was rounded by Telegram before we ever saw it — t.me prints views in full below 1,000 and to three significant figures above, so ≈1,200,000 means somewhere between 1,150,000 and 1,249,999. Unmarked counts are exact. Text is reproduced from the public post preview and truncated for length.
Citation-graph rank — 390,963 of 1,160,990entries in the measured graph. A weighted position computed from the forward and mention edges below — republished posts weigh more than named mentions — and recomputed periodically, over the whole graph. Published only as this ordinal position, never as a score: a position is a fact, and a score printed beside one channel’s name would read as a verdict this register does not make. The two counts beneath stay separate for the same reason mentions are never summed with forwards anywhere else on this page — a named-by count costs nothing to manufacture. The top 100 by this measure, or how it is computed.
Named by 1 registered channel — every channel on the register whose own posts have named this one, by its current username or any other username it currently holds, merged from two separately captured readings of the same fact so a namer caught by only one of them is not missed and a namer both caught is not counted twice. A username this channel has since dropped is not matched — that handle may belong to someone else now, and crediting today’s namer to yesterday’s owner would misattribute it.
Named by
Channels on the register whose posts name this channel's handle.
A mention is a weaker signal than a forward and is counted separately for that reason — naming a channel is not republishing it, and a handle in a post body is easy to place deliberately. The post counts beside each row below are distinct posts in which the handle appeared, from posts we have read on both sides — the “Named by N registered channels” figure above is a different count, of distinct NAMING CHANNELS rather than posts, and is not the sum of the rows under it.
A live page changes as we take new readings, so a citation should name the measurement it is based on, not just the URL. The line below cites the subscriber count as measured 8 August 2026 — this entry's latest reading, not the date you are reading this.
“Math from Krach” (@MathfromKrach), 149 subscribers as measured 8 August 2026. Telegram Register, tgregister.com/channel/MathfromKrach.
Full measurement history, CC BY 4.0. Every reading this register holds for this entry, not just the latest one, as a dated, downloadable record: CSV · JSON. Free to use with attribution to tgregister.com. Each file carries its own generation timestamp, which is the figure to cite for exactly when the data was retrieved.