# ps2 - sentence into a ‘circuit diagram’ Identify the...

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1 Philosophy 220A Symbolic Logic I Instructor: Richard Johns Problem Set 2 Submit answers to the following questions at the start of class on Thursday, Sept. 24. [There are four pages of questions. Make sure that you do them all.] 1 . If the following argument is valid, provide an informal proof. If it isn’t valid then draw a counterexample world. (N.B. Adjoining blocks must be in adjacent cells that share a side in common, not diagonally touching cells.) Adjoins(a, b) Adjoins(a, c) BackOf(b, a) -------------------- FrontOf(c, a) 2 . Show that the following argument is valid by providing a formal proof. Tet(a) a = b c = b ------------- Tet(c) 2.24 (From textbook) For this question and 2.26, do an informal proof if the argument is valid. (Not, as the book says, a formal proof.) 2.26 (From textbook)

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2 3. Translate each ‘circuit diagram’ below into a FOL sentence, and translate each FOL

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Unformatted text preview: sentence into a ‘circuit diagram’. Identify the type of each sentence, e.g. “conjunction sentence’, ‘negation sentence’, or ‘disjunction sentence’. This is determined by the function on the far right of the circuit diagram. (i) (ii) (iii) (iv) (v) ¬ (((P ∨ Q) ∧ R) ∨ S) (vi) ¬¬ (( ¬ P ∨ ¬ Q) ∨ R) ∧ S 3 4 . Calculate the truth value of each of the following sentences in the world shown below. (Please do not use the program Tarski’s World to generate your answers – figure it out yourself. You may, however, use the program to check your answers.) 5 . Draw a world in which all the sentences from Qu. 4 are true. (A couple of modifications to the world shown will do it.) 4 3.14 (From textbook) 3.15 (From textbook)...
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## This note was uploaded on 11/03/2009 for the course ECON 210 taught by Professor James during the Spring '09 term at UBC.

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ps2 - sentence into a ‘circuit diagram’ Identify the...

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