Renju

Key takeaways

Renju belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Renju to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Renju from memory before moving on to harder problems.

Reference excerpt

Renju (Japanese: 連珠) is a professional variant of the abstract strategy board game gomoku. It was named renju by Japanese journalist Ruikou Kuroiwa (黒岩涙香) on December 6, 1899, in a Japanese newspaper Yorozu chouhou (萬朝報). The name "renju" means "connected pearls" in Japanese. The game is played with black and white stones on a 15×15 gridded go board. The rule of renju weakens the advantages for the first player (Black) in gomoku by adding special restrictions for Black.

Rules Renju has its origins in gomoku and therefore shares most of its rules. There are two key differences between these games, however. First, renju has the rule of forbidden moves to limit Black's advantage, something gomoku does not have. Second, renju utilizes special opening rules to balance the starting positions of games.

Forbidden moves There are certain moves that Black is not allowed to make:

Double three – Placing a stone on an intersection, which makes more than one three that meet each other in this intersection. Three – A row with three stones to which one can add one more stone to attain a straight four. Straight four – An unbroken row with four stones to which one can add one more stone to attain five in a row in two different ways. Double four – Placing a stone on an intersection, which makes more than one four that meet each other in this intersection. Four – A row with four stones to which one can add one more stone to attain five in a row. Overline – Six or more stones in an unbroken row. If Black makes a forbidden move, then the game will be won for White. One exception is that, if Black makes a forbidden move and attains five in a row at the same time, it will still be considered a win for Black.

Pass In the game, a player has the option to give up the right to place a stone on the board, which is referred to as passing. If both players choose to pass consecutively, the game is regarded as a draw. The right of passing is usually used when the board is almost full and Black will make an overline if he places a stone on the board.

Winning Black can win the game only by placing exactly five black stones in a row (vertically, horizontally or diagonally). White can win by either:

Getting five (or more) white stones in a row Forcing Black to make a forbidden move (see above).

Opening rules Unlike gomoku, renju has a unique sequence of opening moves called an "opening rule". There are several certified opening rules. The list of requirements for new opening rules as approved by the Renju International Federation (RIF) in 2003 was: I. Traditions

The basic renju rules must be kept. The opening stage must not exceed 5 moves. All 26 canonical openings must be possible and only 26 canonical openings can be possible. All present realistic variants must be possible. The moves located very closely near the edges of a board during the opening stage are not preferable. II. Simplicity and attraction

New rules must be simple to study. New rules must be simple to play for beginners. The situation when in significant part of cases a beginner will have the lost position already after the first 5 moves is not good. The rules must be systematic and attractive. III. Creativity

The number of possible creative variants must be significantly greater than now. These variants must be achieved under the optimal strategy of both players. The chances of sides to win must be practically equal. The situation when during the opening stage the player who make a move does not interested in the forming of equal and creative position is not preferable. (Example: indirect 2nd move in previous opening rules). The rules must give the chance for both players to avoid the position after the opening stage well known for the opponent. The knowledge of theory and deep own analyses must give an advantage but the player with a good imagination must have chances against this. An example of such opening rule (namely "RIF opening rule") follows.

The first player places 2 black stones and 1 white stone on the board thus forming opening pattern. The second player now chooses whether to play black or white. White then places one more stone on the board. Black places 2 stones on the board. White removes one of the two black stones from the previous move. White places a white stone. After this sequence is complete, Black and White continue to take turns to place their stones. The Extra General Assembly of Renju International Federation in 2008 created three new sets of rules for openings that are to replace the above old sequence of moves: Soosõrv, Taraguchi, and Yamaguchi. Also a rejection system for their use was approved. The General Assembly of Renju International Federation in 2009 certified Sakata opening rule as proposed by Russia. The General Assembly of Renju International Federation in 2011 certified modified opening rules such as Taraguchi-N and Soosõrv-N. For the opening rule of both the World Renju Championship and the Team World Renju Championship, Swap opening rule was used before 1996. However, during the Extra General Assembly 1996, RIF opening rule was approved as the official rule for World Championships, starting from World Championship 1997. Subsequently, the official rule was changed to Yamaguchi opening rule from World Championship 2009, during the Extra General Assembly 2008. Then, during the General Assembly 2015, the official rule was changed once again to Soosõrv-8 opening rule from World Championship 2017.

Renju International Federation

The Renju International Federation (RIF) is an international organization which was founded in Stockholm, Sweden on August 8, 1988. The main purpose of the Renju International Federation is to unite all the renju and gomoku national federations all over the world, organize international tournaments and other activities in renju and gomoku, and spread renju activities in the world. The federation carry out the General Assembly every two years.

World Championships

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Illustrations

Worked examples

Example 1 — a first encounter with Renju

Start with the simplest possible case. Write down what Renju claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Renju before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Renju ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Renju

In research: Renju appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Renju in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Renju is common in secondary-school and first-year university syllabi. It links to neighbouring topics Abstract strategy games, Games played on Go boards, Gomoku, so understanding it makes those chapters shorter.
In everyday life: Look for Renju outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Renju in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Renju means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Renju out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Renju in simple terms?

Renju (Japanese: 連珠) is a professional variant of the abstract strategy board game gomoku. It was named renju by Japanese journalist Ruikou Kuroiwa (黒岩涙香) on December 6, 1899, in a Japanese newspaper Yorozu chouhou (萬朝報).

Why does Renju matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Renju?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Renju.