OpenLLM-France/wikimedia huggingface dataset:
# Four-Player Chess/Common openings/1. f4

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Common moves: 1...c8 1...c7 1...c6 1...d6

## English Opening, 1.f4

Red aims to develop the queen to f2 or e3 or exchange queens with Blue.

### Blue's responses

Blue can choose to offer a queen exchange with c6 or d6 or play a normal developing move like c8 or c7.

#### 1...c8

The move c8 opens diagonals for the queen and bishop and appears to be the most active reply by Blue. Blue cannot develop the queen immediately, however, since that would leave b6 undefended.

#### 1...c7

With c7 Blue opens on the light squares.

#### 1...c6

Blue offers a queen exchange.

#### 1...d6

Blue offers a queen exchange, but pushes the pawn two squares rather than one.
# Four-Player Chess/Common openings/1. g3

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B-0,0,0,0-1,1,1,1-1,1,1,1-0,0,0,0-1- 3,yR,yN,yB,yK,yQ,yB,yN,yR,3/ 3,yP,yP,yP,yP,yP,yP,yP,yP,3/ 14/ bR,bP,10,gP,gR/ bN,bP,10,gP,gN/ bB,bP,10,gP,gB/ bK,bP,10,gP,gQ/ bQ,bP,10,gP,gK/ bB,bP,10,gP,gB/ bN,bP,10,gP,gN/ bR,bP,10,gP,gR/ 6,rP,7/ 3,rP,rP,rP,1,rP,rP,rP,rP,3/ 3,rR,rN,rB,rQ,rK,rB,rN,rR,3
Common moves: 1...c8

## Queen's Pawn Opening, 1.g3

This opening (also called 'opening white') is far less common than the move to h3, especially amongst good players. In it Red opens up his white square diagonal for his white squared bishop, and prepares his queen for a one square lift where she can check either green or blue. It has the advantage of an immediate check against Green, but does little immediately against blue.

### Blue's responses

The most common reply by Blue is c8, opening the dark squares for his queen and bishop. The other opening used by good players in this situation is c6.
# Four-Player Chess/Common openings/1. g4

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Common moves: 1...c8

## Double Push Queen's Pawn Opening, 1.g4

Red pushes the queen's pawn two squares. This does not weaken the position as much as h4, since the pawn is supported by the queen and Red may follow up with moves like Bg2, Qg2 or Nf3.

### Blue's responses

If Red opens with the queen's pawn, Blue usually replies with c8 to develop the queen and dark-squared bishop.
# Four-Player Chess/Common openings/1. Ni3

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Common moves: 1...c8 1...c7

## King's Knight Opening, 1.Ni3

Red plays the slightly unusual move Ni3, perhaps looking for an early knight attack against Green.

### Blue's responses

Blue normally wants to develop the queen and bishop(s), so he plays c8 or c7.
# Four-Player Chess/Common openings/1. h3/1...d6

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Y-0,0,0,0-1,1,1,1-1,1,1,1-0,0,0,0-2- 3,yR,yN,yB,yK,yQ,yB,yN,yR,3/ 3,yP,yP,yP,yP,yP,yP,yP,yP,3/ 14/ bR,bP,10,gP,gR/ bN,bP,10,gP,gN/ bB,bP,10,gP,gB/ bK,bP,10,gP,gQ/ bQ,bP,10,gP,gK/ bB,2,bP,8,gP,gB/ bN,bP,10,gP,gN/ bR,bP,10,gP,gR/ 7,rP,6/ 3,rP,rP,rP,rP,1,rP,rP,rP,3/ 3,rR,rN,rB,rQ,rK,rB,rN,rR,3
Common moves: 1...g12 - Classical Sicilian 1...h12 - Modern Sicilian 1...h11 - Hypermodern Sicilian

## Sicilian Defence, 1...d6

Blue blocks the dark-squared a9-i1 diagonal with a pawn, giving him the option to play the move c8 next, if Red does not take the pawn with the bishop.

### Yellow's responses

Yellow can choose between opening on the dark squares, like Red, or doing the opposite and opening on the light squares. The former is the classical way of playing and may lead to a symmetrical opening that is generally known as the "Classical opening", in which Red and Yellow develop their queens to j4 and e11, respectively, and Blue and Green develop their queens to b7 and m8. The latter is more modern and aims to coordinate threats along the light- and dark-squared diagonals. The most common moves for Yellow are g12 and h12 and somewhat less common is h11, pushing the queen's pawn two squares.

#### Classical Sicilian, 1...g12

This classical move has regained popularity recently.

#### Modern Sicilian, 1...h12

The idea of this move is to do the opposite of Red and open on the light squares to coordinate better with Red and create threats along both the dark- and light-squared diagonals. The follow-up is usually Qh13, potentially creating a mating threat on Blue together with the Red queen, if she can attack b9 or b7 later on, for instance with the manoeuvre Qg1-k5-g9. Yellow can also target Green with a move like Bg12, attacking Green's natural weakness on m6. This plan can be very dangerous, but there are sufficient defensive resources available to Blue and Green. In the long term the bishop can be slightly misplaced on g12, but usually it will either be sacrificed or moved to h11, taking control over the long diagonal.

#### Hypermodern Sicilian, 1...h11

This move has an idea similar to h12, but pushing the pawn one square further gives Yellow another option to develop the queen to h12. It does take away the option to play Bg12 and target Green's weakness on m6.
# Four-Player Chess/Common openings/1. h3/1...d6/1...g12

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Common moves: 1...l9 1...k9 1...l8 1...Nl6

## Classical Sicilian, 1...g12

Yellow also opens up the dark-squared diagonals.
# Exercise as it relates to Disease/The effects of exercise on osteoporosis sufferers

Osteoporosis is the most common type of bone disease; it is a weakening of the bones over time due to the loss of minerals, primarily calcium and phosphorous, resulting in a thinning of the bones and a gradual decrease in bone density. Bone production is dependent upon the body obtaining an adequate and ongoing supply of calcium and phosphate in the diet. Failure to obtain adequate supplies of these minerals will result in poor bone growth in youth and re-absorption of the minerals by the body from existing bone, weakening the bone tissue, usually later in life. This decrease in the density of the bones makes them brittle and prone to fracture.

## Causes

The major cause of osteoporosis in older people are the reduction in estrogen levels in women during menopause and a drop in testosterone levels in men often associated with aging. Other causes of osteoporosis include:
* Medical conditions such as hyperparathyroidism and chronic kidney disease
* Extensive periods of inactivity such as being confined to a bed
* Insufficient calcium in the diet often associated with eating disorders
* Smoking, alcohol and drug (corticosteroids) abuse
* Vitamin D deficiency

## Effects

The early stages of osteoporosis do not produce any appreciable signs or symptoms and often the disease may remain undetected until an osteoporotic fracture occurs. As the condition progresses some or all of the following symptoms may become apparent:
* Fractures associated with little or even no appreciable trauma
* Neck and lower back pains due to fractures of the vertebra
* Loss of height
* Changes in posture such as developing a kyphotic stoop or dowagers hump on the back

## Treatments

Treatments for osteoporosis include Lifestyle changes, such as taking part in structured resistance training programs, which, when combined with a diet with a higher intake of calcium and phosphorous, will serve to force the body to lay down new bone with a much more rigid structure than the fragile osteoporotic bone. Other treatments include Medications such as HRT therapy, Biophosphates, Calcitonin and Raloxifene

## Prevention

Prevention of the onset of osteoporosis is the preferred approach. The risk of incurring the condition can be reduced by:
* Following a healthy balanced diet including Vitamin D and calcium rich foods
* Avoidance of smoking and excess consumption of alcohol
* Regular exercise, consisting of weight bearing/resistance training and cardio routines.

## References & Further Reading

* Prof M. A. Fiatarone Singh. Exercise & Fracture Prevention, A guide for GP’s and Health Professionals. December 2006 – January 2007 http://www.osteoporosis.org.au/images/stories/documents/internal/oa_exercise_gphp.pdf
* Associate Professor Nicholas Pocock MD, FRACP - Osteoporosis, Health insite Australia. March 2007 http://www.healthinsite.gov.au/expert/Osteoporosis
* http://www.who.int/en/
# Guide to Unix/Explanations/Firewalls
## Introduction to Firewalls
### The Concept of Firewall

A software Firewall is a filter of network traffic, in the form of Packets. Each packet contains information such as senders' IP, receivers' IP. Firewall rules are criteria, which are set based on the information of the packet.
There are two types of firewall, based different logic conditions. Exclusive firewall allows all traffic except for the traffic matching the ruleset. Inclusive firewall denies all traffic except for the traffic matching the ruleset.
Note: Firewalls are known as "packet filter". Other related concepts are "packet shaper". It controls bandwidth based on rulesets.
# Guide to Unix/Explanations/Connecting to Remote Unix

If the shell prompt is on a remote server, ssh is the most common way to access it. The server must be running the sshd server software to accept your connection. The SSH protocol encrypts your connecting to prevent spying and stealing of passwords. All that is required is that you trust the computer that you connect from and the server where your account is located.
To connect, open your SSH client, specify the name of the server and your username. Most servers use the default port 22, so specifying the port is not necessary. (Be careful with ports 1024 and higher because these are controlled by users, not the system administrator.)

#### Using SSH from a Shell Prompt

To connect to one Unix-like system from another, you can the ssh shell command. This command is often OpenSSH, a popular SSH implementation from OpenBSD. For example, Tux wants to connect to an account (username tux) on the computer "linux.example.edu":
If Tux has the same username on the local computer, then specifying the username is optional:

#### Accepting the Key Fingerprint

The first time you connected, you saw a message similar to the following:
If you are reasonably sure that you connected to the correct computer (an attacker on the Internet might steal your connection to learn passwords) then you can answer 'yes' and add linux.example.edu to the list of known hosts. Some SSH clients also allow you to say 'yes' to one session only.
When you say 'yes', you get a message such as: Warning: Permanently added 'linux.example.edu,1.2.3.4' (RSA) to the list of known hosts.
This means that your SSH client "knows" linux.example.edu. It will verify that future connections to "linux.example.edu" reach the same computer (or cluster). You will be alerted if an attacker steals your connection, but also if linux.example.edu changes its key. Thus, if you know that linux.example.edu changed its key and you recognize the key, then you can ignore the alert.

## graphical connections

Most tasks on a Unix machine can be done in text mode, from the shell prompt.
However, once the text-mode ssh connection is working, many people feel more comfortable switching to a graphical interface.
A typical setup has a VNC viewer on the local end and a X11/VNC server on the remote end, and a ssh tunnel. (Any VNC viewer -- including ssvnc, sshvnc, or a Java-enabled web browser -- will work with any VNC server). The ssh software grabs all information that would normally flow through the VNC ports (ports 5900 through 5906 and ports 5800 through 5806) and funnels them through the ssh tunnel (by default, port 22).

## further reading

* Internet Technologies/VNC
* Guide to X11
# Guide to Unix/Explanations/Determining Hardware

Here are some methods of Determining Hardware currently on the system:
* run dmesg (works well on *BSD)
* use KDE Info Center (K Menu -> System -> Info Center)
This page or section of Guide to Unix is a stub. You can help by expanding it.

### Examples

Run dmesg on a *BSD system to determine the kernel version, amount of memory, and whether this computer has an audio device.
This system has an OpenBSD 3.8 kernel, which matches the OpenBSD 3.8 operating system distribution. (Generally, the kernel on a *BSD matches some version of the system. In contrast, there are many combinations of Linux kernels and systems.)
The real memory is 262144K, but only 230824K is "avail", which probably means available. Divide by 1024 to convert to megabytes, using bc or some other method:
This computer has 256 MB of memory, but only 225 MB are "avail". Because we used bc, the answers are rounded down to integers.
This line from the dmesg output indicates the presence of an audio device:
We can go up the dmesg, learning that we have audio0 at snapper0 at macobio0 at pci1 at mpcpcibr1 at mainbus0. However, we are probably only interested in "audio0", which means that we have an audio device, and "snapper0" if we want to know the type of sound card providing this audio. On this computer, it should be possible to install programs that play sound and music.
# Guide to Unix/Explanations/Fake Networking Interfaces
### Loopback

The system uses the loopback interface "lo0" to talk to itself. Most systems automatically configure it at boot. Talking-to-oneself is useful for testing servers, and also for any situation where the server and client are on the same computer. (For example, some computer games have a one-player mode where server and client are on the same computer. These games use the "network", but because there is only one computer, they use the loopback interface.)
Use the ifconfig command to check the status of the interface. It probably looks something like:
The IPv4 address of your computer is "127.0.0.1". This is in addition to any address that it has on an actual network. In fact, every computer calls itself "127.0.0.1", so it is impossible to use this address to communicate between computers. (Some jokes involve a person who is given "127.0.0.1" as an attack target and proceeds to destroy their own computer.)
If your system is running an IPv6 stack, then your IPv6 loopback address is "::1". The computer should be able to use IPv6 to communicate with itself, even if it has no connection to an actual IPv6 network.
You probably have no problem pinging the interface with ping or ping6. We use "ping -c3" and "ping6 -c3" to ping 3 times; otherwise it would ping every second until you interrupted with ^C (CTRL+C).

### Create interfaces

If you want to use a fake network interface, you often must create it with "ifconfig create".
Some interfaces that you might be able to create: bridge, carp, gif, gre, lo, ppp, pppoe, sl, trunk, tun, vlan.
This page or section of Guide to Unix is a stub. You can help by expanding it.
# Guide to Unix/Explanations/Compact Discs
### Ripping CD audio

This copies the audio from a CD track to a file. With some drives (one without analog connections to the sound card) this is the only way to correctly play a file.

#### Granting permission to the user

First you should have read-and-write permission to the CD device. (You could become root to rip the CD, but then you would have to "chown" the file back to you.)
First look at your CD devices nodes. On *BSD, they are at /dev/cd* and /dev/rcd*. If they look like this:
Here, root needs to grant read and write permission to the user. We decide to add the users to group "wheel". Once they are in, we change the group of the devices and grant read and write permission to the group:

#### Ripping tracks

We must insert a CD before ripping the track.
Here, for example, we rip track 2 and store it in song.wav. Our ".wav" suffix is because that is the default format of cdparanoia. With a CD in:

### Eject a disc

Many systems provide an eject command.

### Burn a disk

Scenario: put the contents of a directory called backup to CD.
Here we do the actual burn (and eject) as root. The user needs to have "sudo" access, but not any special access to the CD device node.
Create a disk image of the CD. We will call it burn.iso.
* -R is ISO6990 Rock Ridge support
* -r is Rock Ridge but with all files to root (usable on computers with different users)
* -hfs indicates a hybrid ISO9660/HFS disk
Mount it to check for validity. (NetBSD/OpenBSD)
The filesystem is good though file is misleading:
Insert a blank disk.
This is a test burn to demonstrate cdrecord -v.
An actual burn:
We should eject the finished disk now. The OS or drive might not know that the disk now has a filesystem on it.
If we reinsert the disk then we can mount/unmount it:
This page or section of Guide to Unix is a stub. You can help by expanding it.
# Guide to Unix/Explanations/Finding Additional Help
### Google

Google is your friend. The Internet has a lot of example and command samples to perform tasks. All you have to do is run a search. This is often the only approach because the built in help really requires you to know the command name to start with which is not very useful.
For samples of actual code, you can try the Google code search with the option lang:shell.

### Friends and support groups

You should never be shy of asking for help from knowledgeable people around you. They often will give you a quick answer that you have to research or tune to get the complete answer however it will give you a starting point for the following commands to be truly useful.
This page or section of Guide to Unix is a stub. You can help by expanding it.
# HSC Extension 1 and 2 Mathematics/Trigonometric functions
## Radian measure of an angle

2π radians in a revolution

## Arc length and area of a sector of a circle

$l=r\theta \;$
$A={\frac {1}{2}}r^{2}\theta$
* Where θ is in radians

## Area of a segment of a circle
### Minor segment

$A={\frac {1}{2}}r^{2}(\theta -\sin \theta )$
* Where θ is in radians

### Major segment

$A=\pi r^{2}-{\frac {1}{2}}r^{2}(\theta -\sin \theta )$
* Where θ is in radians

## Definitions of trigonometric functions

In mathematics, the trigonometric functions (also called circular functions) are functions of an angle. They are used to relate the angles of a triangle to the lengths of the sides of a triangle. Trigonometric functions are important in the study of triangles and modeling periodic phenomena, among many other applications.

## Derivative of sin x and cos x

$\sin 'x=\cos x\;$
$\cos 'x=-\sin x\;$

## Derivative of tan x

$\tan 'x=\sec ^{2}x\;$

## Derivative of sin (ax + b)

$\sin '(ax+b)=a\cos(ax+b)\;$

## Derivative of cos (ax + b)

$\cos '(ax+b)=-a\sin(ax+b)\;$