Recapitulaci:

1
Coordination Many social interactions can be
modeled as a coordination game The players have
a common interest, but as there are multiple
equilibria, the desired outcomes are only
achieved if they mutually adjust their actions in
the right way and go for the same equilibrium.
2

• Ejemplos coordinación
• Conducir por el lado derecho.
• Eligir otra ruta en caso de congestión.
• Ancho del tren en América, ancho de las cohetes.
• Bank-run.
• Encontrarse en Barcelona.

3

• Peyton Young (1993) distinguishes three broad
  equilibrium selection theories
• First, some equilibria may be a priori more
  reasonable than others (see, e.g., John Harsanyi
  and Reinhard Selten, 1988).
• Second, it might be that "agents focus their
  attention on one equilibrium because it is more
  prominent or conspicuous than the others" (Peyton
  Young, 1993, p. 58).
• Third, expectations may converge on one
  equilibrium through precedent (see, e.g., Vincent
  Crawford and Hans Haller, 1990).

4

• Exemple de situació amb equilibris múltiples
• Heu descollir un número entre 1 i 7.
• Els guanys del jugador i depenen
• tant del numero escollit pel jugador i, ei,
• com del mínim m minej dels números escollits
  per tots els jugadors,
• segons la formula 0,6 0.2m 0,1ei.
• Això queda resumit en la taula següent

5
Experimento principal Van Huck, Batalio, Beil
(1990, AER) Minimum effort game. 0,6
0.2m 0,1ei
6

• 7 equilibria ranked
• Pareto dominant could be focal
• Conflict between encouraging others to choose
  high number and risk of doing it.
• Pareto-dominant is not always chosen
• With the same 2 players Pareto dominant is
  usually chosen. Not with random pairings, not
  with n large.

7

• Cómo se puede mejorar la coordinación
• Comunicación.
•     Tamaño del grupo.
•     Número de periodos.
•     Costes de entrada.
•     Competición.

8
Horizonte con pocos vs muchos periodos
9
Coordinación con 2 personas (con la misma
pareja vs emparejamiento por azar)
10
Battle of Sexes
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Coordinación con competición
12
Localization problem

• You want to locate where everybody goes (BCN vs
  MAD)
• 7 persons play 15 periods

13

• Results Path Dependence
• Small historical accidents have large long-run
  impact. Lorentz effect
• Extreme sensitivity to initial conditions.
• Predicting in these games is like trying to prove
  that a joke is funny without telling it
• Continental divide two water drops fall
  infinetissimaly close, yet

14
Focal points as a coordination device

• As Thomas Schelling (1960) put it
• "Most situations - perhaps every situation for
  people who are practiced at this kind of game -
  provide some clue for coordinating behavior, some
  focal point for each persons expectation of what
  the other expects him to expect to be expected to
  do. Finding the key, or rather finding a key -
  any key that is mutually recognized as the key
  becomes the key - may depend on imagination more
  than on logic it may depend on analogy,
  precedent, accidental arrangement, symmetry,
  aesthetic or geometric configuration, casuistic
  reasoning, and who the parties are and what they
  know about each other" (p. 57).

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• Conclusión (coordinación)
• Reglas de selección
•        Precedencia (historia importante).
•        Dominancia del riesgo.
•        Pareto optimalidad (no siempre llegamos)
•        Evitar pérdidas.
•        Seguridad (maximización del mínimo de
  todos)
•        Ventaja para el que elige primero.