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title = "Strict evaluation or lazy evaluation of predicates"
date = "2023-02-14"
author = "Yann Herklotz"
tags = []
categories = []
backlinks = ["3c3f6"]
forwardlinks = ["3c3f7a"]
zettelid = "3c3f7"
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Strict evaluation of predicates is the following:
$$\frac{\theta \vdash p_1 \Downarrow b_1 \qquad \theta \vdash p_2 \Downarrowb_2}{\theta \vdash p_1 \land p_2 \Downarrow b_1 \mathbin{\texttt{\&}} b_2}$$
Lazy evaluation of predicates will instead have multiple rules that take
into account when we know the result of the computation:
$$\frac{\theta \vdash p_1 \Downarrow \perp}{\theta \vdash p_1 \land p_2 \Downarrow \perp}$$
$$\frac{\theta \vdash p_2 \Downarrow \perp}{\theta \vdash p_1 \land p_2 \Downarrow \perp}$$
$$\frac{\theta \vdash p_1 \Downarrow \top \qquad \theta \vdash p_2 \Downarrow \top}{\theta \vdash p_1 \land p_2 \Downarrow \top}$$
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