We reveal a symmetric structure in the ho/n games model of innocent strategies, introducing rigid strategies, a concept dual to bracketed strategies. We prove a direct definability theorem of general innocent strategies with respect to a simply typed language of extended Bohm trees, which gives an operational meaning to rigidity in call-byname. A corresponding factorization of innocent strategies into rigid ones with some form of conditional as an oracle is constructed.
['Vincent Danos', 'Russell Harmer']
The Anatomy of Innocence