Abstract
Recall the example on page 3, in which we transcribed in clauses the problem of checking whether a graph G with n vertices is k-colourable. We used n × k variables with the intention that each variable X ij abbreviates the phrase “vertex i has colour j”. Each variable X ij also represents the question “does vertex i have colour j?”, and intends to contain the yes-no answer to this question.
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1 The crucial notion of “step” is taken care of by an ingenious mathematical artefact introduced by Alan Turing in 1936.
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© 2012 Springer-Verlag Italia
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Mundici, D. (2012). Recap: Expressivity and Efficiency. In: Logic: A Brief Course. UNITEXT(). Springer, Milano. https://doi.org/10.1007/978-88-470-2361-1_10
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DOI: https://doi.org/10.1007/978-88-470-2361-1_10
Publisher Name: Springer, Milano
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Online ISBN: 978-88-470-2361-1
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