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Suppose I have a term $a :\alpha$ of the Simply-Typed Lambda Calculus (in the following, $\alpha, \beta, \gamma$ stand for arbitrary types) and I want to lift it to a term $\lambda x_{\beta}. \;(x, \, a)$ I could use a function $\lambda z_{\alpha}, x. \;(x,\, z)$. Suppose we then form $(b, a) : \...