that can be duplicated by a mixture of other actions. Unfortunately, proper equilibrium does not survive the addition/ deletion of such "mixed-duplicated"actions. Correspondingly, it is not always possible to find a sequential equilibrium equilibrium of an extensive game which beautiful example of this in their 1986 paper on strategic stabilify, erg and Mertens have a survives the addition/deletion of a mixed-duplicated action: Kohlbthat can be duplicated by a mixture of other actions. Unfortunately, proper equilibrium does not survive the addition/deletion of such “mixed-duplicated” actions. Correspondingly, it is not always possible to find a sequential equilibrium equilibrium of an extensive game which survives the addition/deletion of a mixed-duplicated action: Kohlberg and Mertens have a beautiful example of this in their 1986 paper on strategic stability. 7