[16] Together with Elon Kohlberg, he applied operator techniques to study convergence properties of the discounted and finite stage values.
[17] Recently, he has pioneered a model of stochastic games in continuous time and derived uniform equilibrium existence results.
A related insight appears in a 1999 paper, where he showed that in a long finitely repeated game, an exponentially small deviation from common knowledge of the number of repetitions is enough to dramatically alter the equilibrium analysis, producing a folk-theorem-like result.
In his seminal paper[21] he showed that bounded memory can justify cooperation in a finitely repeated prisoner's dilemma game.
[22] The two main models of bounded complexity, automaton size and recall capacity, continued to pose intriguing open problems in the following decades.
A major breakthrough was achieved when Neyman and his Ph.D. student Daijiro Okada proposed a new approach to these problems, based on information theoretic techniques, introducing the notion of strategic entropy.
[23][24] His students continued to employ Neyman's entropy technique to achieve a better understanding of repeated games under complexity constraints.
Together with Pradeep Dubey and Robert James Weber he studied the theory of semivalues, and separately demonstrated its importance in political economy.
[30][31] Together with Pradeep Dubey [32][33] he characterized the well-known phenomenon of value correspondence, a fundamental notion in economics, originating already in Edgeworth's work and Adam Smith before him.
[39] In 1999, Neyman co-founded Bidorbuy, the first online auction company to operate in India and in South Africa, and serves as the chairman of the board.