Merge pull request #428 from Axelrod-Python/403

403 Adding play contexts and RPST to docs

Author: meatballs

docs/background/background.rst docs/reference/description.rstdocs/background/background.rst renamed to docs/reference/description.rst

@@ -8,5 +8,7 @@ Contents:
 .. toctree::
    :maxdepth: 2
 
+   description.rst
+   play_contexts.rst
    overview_of_strategies.rst
    glossary.rst

docs/reference/index.rst

@@ -0,0 +1,37 @@
+Play Contexts and Generic Prisoner's Dilemma
+============================================
+
+There are four possible round outcomes:
+
+- Mutual cooperation: :math:`(C, C)`
+- Defection: :math:`(C, D)` or :math:`(D, C)`
+- Mutual defection: :math:`(D, D)`
+
+Each of these corresponds to one particular set of payoffs in the following
+generic Prisoner's dilemma:
+
+
++----------+---------------+---------------+
+|          | Cooperate     | Defect        |
++==========+===============+===============+
+|Cooperate | (R,R)         | (S,T)         |
++----------+---------------+---------------+
+|Defect    | (T,S)         | (P,P)         |
++----------+---------------+---------------+
+
+For the above to constitute a Prisoner's dilemma, the following must hold:
+:math:`T>R>P>S`.
+
+These payoffs are commonly referred to as:
+
+- :math:`R`: the **Reward** payoff (default value in the library: 3)
+- :math:`P`: the **Punishment** payoff (default value in the library: 1)
+- :math:`S`: the **Sucker** payoff (default value in the library: 0)
+- :math:`T`: the **Temptation** payoff (default value in the library: 5)
+
+A particular Prisoner's Dilemma is often described by the 4-tuple: :math:`(R, P,
+S, T)`::
+
+    >>> import axelrod
+    >>> axelrod.game.DefaultGame.RPST()
+    (3, 1, 0, 5)