Def b == if b false else true fi

is mentioned by

Def rep_sum Def == u:'a+'b. InjCase(u Def == u:'a+'b. InjCase; p. b:. x:'a. y:'b. (x = p)b Def == u:'a+'b. InjCase; q. b:. x:'a. y:'b. (y = q)b)

[hrep_sum]

In prior sections: bool 1 union hol hol bool

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