Discord is useless if you want to participate in more than one large group because of this. It is impossible to get email notification for selected threads you care about.
No way to get email notifications for missed activity? support.discord.com/hc/en-us/community/posts/360041806392-Can-we-get-an-email-notification-option-for-messages-
The Shannon number, named after the mathematician and electrical engineer Claude Shannon, is an estimate of the lower bound of the game-tree complexity of chess. It represents the total number of possible unique chess positions that can arise during a game. The Shannon number is approximately \(10^{120}\), which illustrates the vast complexity of chess and indicates that there are far more possible chess games than there are atoms in the observable universe.
Adam Marcus is an American mathematician known for his work in the fields of combinatorics and algebra. He gained recognition for his contributions to various mathematical problems and theories. One notable achievement is his work on the existence of certain types of combinatorial structures, which has implications in theoretical computer science and discrete mathematics. In addition to his research, Adam Marcus has also collaborated with other mathematicians, including Nikhil Srivastava and Daniel A.
Anatoly Vershik is a prominent Russian mathematician known for his contributions to various areas of mathematics, particularly in the fields of probability theory, statistics, and mathematical analysis. He has worked extensively on stochastic processes, ergodic theory, and combinatorial mathematics. Vershik is also recognized for his research on the representation theory of groups and their applications to mathematical physics. He has published numerous papers and has been influential in advancing mathematical understanding in these areas.
The Ainu creation myth is part of the indigenous Ainu culture of Japan, particularly associated with the northern regions such as Hokkaido. The Ainu have a rich oral tradition, and their mythological stories illustrate their understanding of the world, nature, and their relationship with the divine. In Ainu creation myths, the world is often described as being formed from the sea. One notable myth starts with the god of the sea, who created the first land.
Topological dynamics is a branch of mathematics that studies the behavior of dynamical systems through the lens of topology. It focuses on how systems evolve over time while considering the global structure of the space in which they reside. The central objects of study in topological dynamics are often continuous functions on topological spaces that model the evolution of a system.
"Numbers" can refer to several different concepts depending on the context. Here are a few possible interpretations: 1. **Mathematical Concept**: In mathematics, numbers are symbols used to represent quantities and are fundamental to counting, measuring, and performing various calculations. They include various types such as natural numbers, whole numbers, integers, rational numbers, irrational numbers, and real numbers.
ENO methods, or Essentially Non-Oscillatory methods, are a class of numerical techniques used primarily for the solution of hyperbolic partial differential equations (PDEs). They are particularly valuable for problems where shock waves or discontinuities are present, as they help prevent artificial oscillations that can occur in traditional numerical methods.
In the context of mechanical systems, structural dynamics, or control theory, a **damping matrix** is a mathematical representation that describes the damping characteristics of a system. Damping refers to the effect that dissipates energy (often in the form of heat) from vibrating systems, and it is critical for controlling oscillations and improving stability.
Leon Glass is a notable figure in the field of neuroscience, particularly known for his contributions to the understanding of neuronal dynamics and the mechanisms of brain function. He has been influential in the study of how neural circuits operate, especially in relation to rhythm generation and the synchronization of networks of neurons.
Continuous optimization refers to the process of finding the best solution (maximum or minimum) of an objective function that is defined over continuous variables. This contrasts with discrete optimization, where variables can only take on discrete values (such as integers). In continuous optimization, the decision variables can take on any value within a defined range. ### Key Concepts in Continuous Optimization: 1. **Objective Function**: This is the function that needs to be maximized or minimized. It describes the goal of the optimization problem.
Mental calculation refers to the process of performing arithmetic calculations in one’s mind without the use of external tools such as calculators, pen, or paper. It involves using cognitive abilities to manipulate numbers, solve problems, and derive answers based on mental arithmetic techniques. Key aspects of mental calculation include: 1. **Speed**: Mental calculations aim to achieve quick results, allowing individuals to solve problems efficiently. 2. **Accuracy**: While speed is important, maintaining accuracy in calculations is crucial to ensure reliable results.
A subtractor is a digital circuit that performs subtraction on binary numbers. It is commonly used in arithmetic logic units (ALUs) and various computing applications. The simplest form of a subtractor is a **half subtractor**, which takes two input bits and produces a difference and a borrow output. A more complex version is the **full subtractor**, which handles borrowing from previous bits, allowing it to subtract multi-bit binary numbers.
Bayesian networks, also known as belief networks or Bayes nets, are a type of graphical model that represent a set of variables and their conditional dependencies using a directed acyclic graph (DAG). In a Bayesian network: 1. **Nodes** represent random variables, which can be discrete or continuous. 2. **Directed Edges** indicate causal relationships or dependencies between the variables. An edge from node A to node B suggests that A has some influence on B.
AdS black holes refer to black holes that are solutions to Einstein's equations in a spacetime with anti-de Sitter (AdS) symmetry. Anti-de Sitter space is a five-dimensional (or higher) spacetime that has a constant negative curvature, which can be visualized as a hyperbolic geometry. This spacetime is a key feature of certain theories in theoretical physics, particularly in the context of string theory and holographic duality.
"Pritam Deb" does not refer to a widely recognized or notable concept, person, or entity as of my last knowledge update in October 2023. It's possible that "Pritam Deb" could refer to an individual or a specific context that may not be broadly known or has emerged after that date.
On Ubuntu 20.10 PostgreSQL 12.6, login with
psql on my default username without sudo fails with: stackoverflow.com/questions/11919391/postgresql-error-fatal-role-username-does-not-existThis is the one that worked on Ubuntu 21.04: stackoverflow.com/questions/11919391/postgresql-error-fatal-role-username-does-not-exist/38444152#38444152Explanation:
sudo -u postgres createuser -s $(whoami)
createdb $(whoami)You can now run shows that peer authentication is available to all users apparently:
psql without any password. This works without password due to peer authentication:sudo cat /etc/postgresql/12/main/pg_hba.conflocal all postgres peer
# TYPE DATABASE USER ADDRESS METHOD
# "local" is for Unix domain socket connections only
local all all peerList users:output:
psql -c '\du' List of roles
Role name | Attributes | Member of
-------------+------------------------------------------------------------+-----------
ciro | Superuser, Create role, Create DB | {}
owning_user | | {}
postgres | Superuser, Create role, Create DB, Replication, Bypass RLS | {}Delete user later on:
psql -c 'DROP USER username;'Help toplevel:
helpList supported SQL commands:
\hShow syntax for one type of command:
\h SELECTList all databases:which shows:
psql -c '\l' Name | Owner | Encoding | Collate | Ctype | Access privileges
-------------+----------+----------+-------------+-------------+-----------------------
ciro | postgres | UTF8 | en_GB.UTF-8 | en_GB.UTF-8 |
postgres | postgres | UTF8 | en_GB.UTF-8 | en_GB.UTF-8 |
template0 | postgres | UTF8 | en_GB.UTF-8 | en_GB.UTF-8 | =c/postgres +
| | | | | postgres=CTc/postgres
template1 | postgres | UTF8 | en_GB.UTF-8 | en_GB.UTF-8 | =c/postgres +
| | | | | postgres=CTc/postgres
testdb0 | postgres | UTF8 | en_GB.UTF-8 | en_GB.UTF-8 |
(6 rows)If you didn't give a database from the command line e.g.:you can do that afterwards with:
psql\c testdb0Let's create a table and test that it is working:
psql testdb0 -c 'CREATE TABLE table0 (int0 INT, char0 CHAR(16));'List tables, no special tables:gives:
psql testdb0 -c '\dt' List of relations
Schema | Name | Type | Owner
--------+--------+-------+-------
public | table0 | table | ciro
(1 row)View table schema: stackoverflow.com/questions/109325/postgresql-describe-tableoutput:
psql testdb0 -c '\d+ table0' Table "public.table0"
Column | Type | Collation | Nullable | Default | Storage | Stats target | Description
--------+---------------+-----------+----------+---------+----------+--------------+-------------
int0 | integer | | | | plain | |
char0 | character(16) | | | | extended | |Insert some data into it and get the data out:output:
psql testdb0 -c "INSERT INTO table0 (int0, char0) VALUES (2, 'two'), (3, 'three'), (5, 'five'), (7, 'seven');"
psql testdb0 -c 'SELECT * FROM table0;' int0 | char0
------+------------------
2 | two
3 | three
5 | five
7 | seven
(4 rows)Delete the table:
psql testdb0 -c 'DROP TABLE table0;' Pinned article: ourbigbook/introduction-to-the-ourbigbook-project
Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
Intro to OurBigBook
. Source. We have two killer features:
- topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculusArticles of different users are sorted by upvote within each article page. This feature is a bit like:
- a Wikipedia where each user can have their own version of each article
- a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
Figure 1. Screenshot of the "Derivative" topic page. View it live at: ourbigbook.com/go/topic/derivativeVideo 2. OurBigBook Web topics demo. Source. - local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
- to OurBigBook.com to get awesome multi-user features like topics and likes
- as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
Figure 2. You can publish local OurBigBook lightweight markup files to either OurBigBook.com or as a static website.
Figure 3. Visual Studio Code extension installation.
Figure 5. . You can also edit articles on the Web editor without installing anything locally. Video 3. Edit locally and publish demo. Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension. 
- Infinitely deep tables of contents:
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact