(b) (i) The following two formulas are two ways of saying "all cars have four wheels": Vcar.hasFour Wheels(car) Vr.car(r) → hasFour Wheels(r) With reference to how formulas in predicate logic are interpreted in a universe, explain the difference between these two ways of expressing "all cars have four wheels". (ii) Assume now that the universe consists of websites and that we are working in a vocabulary with a single predicate symbol links To of arity 2, with the intended meaning that linksTo(2, y) holds when z links to y. State the following English sentences as Predicate Logic formulas in this vocabulary: 1. Every website links to itself. 2. Every website links to some other website.

(b) (i) The following two formulas are two ways of saying "all cars have four wheels": Vcar.hasFour Wheels(car) Vr.car(r) → hasFour Wheels(r) With reference to how formulas in predicate logic are interpreted in a universe, explain the difference between these two ways of expressing "all cars have four wheels". (ii) Assume now that the universe consists of websites and that we are working in a vocabulary with a single predicate symbol links To of arity 2, with the intended meaning that linksTo(2, y) holds when z links to y. State the following English sentences as Predicate Logic formulas in this vocabulary: 1. Every website links to itself. 2. Every website links to some other website.

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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