Assignment 14

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course mth 151

014. `query 14

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Question: `q3.3.5 rewrite using if then ' all marines love boot camp '.

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Your solution:

If they are a marine, then they love boot camp.

confidence rating #$&*: 3

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Given Solution:

`a** The statement is equivalent to 'If it's a Marine, it loves boot camp' or equivalent.

The statement is not equivalent to 'if it is boot camp, then all Marines love it', which is the converse of the original statement. **

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Self-critique (if necessary):ok

Do you have to use it or can you use they like I did above???????

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Self-critique Rating:

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We don't worry much about the grammar. Your answer would be fine.

However, with regard to the grammar, 'they' is plural and 'a marine' is singular, which is a grammatical mismatch. Again we aren't going to be strict with grammar here, so that's just FYI.

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Question: `q3.3.18 ~p false q false p -> q true

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Your solution:

This is a little confusing but I think that if p is true because ~p is false, and q is false then the latter can’t possibly be true because one is true and one is false…

confidence rating #$&*: 2

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Given Solution:

`a** Since ~p is false then p is true.

Since q is false it follows that p -> q is of the form T -> F, which is false.

The conditional is false when, and only when, the antecedent is true and the consequent false. **

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Self-critique (if necessary):ok

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Self-critique Rating:

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Question: `qQuery 3.3.36 write in symbols 'If we don't bike, then it does not rain.'

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Your solution:

~p->~q

If p stands for the activity of biking and q stands for the action of it raining then you would negate each one and make them equivalent.

confidence rating #$&*: 2

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Given Solution:

`a** If p stands for 'don't bike' and r for 'it rains' then the statement would be p -> ~r. **

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Self-critique (if necessary):

Why wouldn’t you negate both of them??????? And is it okay that I used q instead of r???????

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Self-critique Rating:

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Question: `qQuery 3.3.48 q true, p and r false, evaluate (-r U p) -> p

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Your solution:

I think it would be false because p is said to be false.

confidence rating #$&*: 2

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Given Solution:

`a** The antecedent (~r U p ) would be true, since ~r true and p false.

The consequent p would be false.

Since the antecedent is true and the consequent false, the conditional is false. **

MORE DETAILED SOLUTION

r is said to be false, so ~r is true

p is said to be false

Therefore the disjunction (~r U p) would be a disjunction of a true and a false statement.

A disjunction is true if at least one of the statements is true, so (~r U p) is true.

The conditional (~r U p) -> p therefore consists of an antecedent which is true, and a consequent which is false.

By the rules for a conditional, the statement is therefore false.

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Self-critique (if necessary):ok

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Self-critique Rating:

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&#Your response did not agree with the given solution in all details, and you should therefore have addressed the discrepancy with a full self-critique, detailing the discrepancy and demonstrating exactly what you do and do not understand about the parts of the given solution on which your solution didn't agree, and if necessary asking specific questions (to which I will respond).

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Question: `qQuery 3.3.60 truth table for (p ^ q) -> (p U q)

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Your solution:

T T T T T

T F F T T

F T F T T

F F F F T

confidence rating #$&*: 3

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Given Solution:

`a** The headings would be p, q ,(p^q), (pUq), (p^q)->(pUq)

Row 1 would read T T T T T

Row 2 would read T F F T T

Row 3 would read F T F T T

Row 4 would read F F F F T

The common sense of this is that whenever both p and q are true, then the statement 'p or q' must be true. That's what means to say (p ^ q) -> (p U q).

The fact that this statement is true is indicated by the last column of the truth table, which has True in every possible case. **

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Self-critique (if necessary):ok

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Self-critique Rating:

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Question: `qQuery 3.3.74 (formerly 3.3.72). This wasn't assigned but it is similar to assigned questions and should be answered: What is the negation of the statement 'if loving you is wrong then I don't want to be right' ?

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Your solution:

If loving you is right then I don’t want to be right

confidence rating #$&*: 2

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Given Solution:

`a** The negation has to have the exact opposite truth values of the original statement.

It is difficult and confusing to try to negate a conditional. It is much easier to translate the conditional to a disjunction then negate the disjunction. It is easy to negate the disjunction using deMorgan's Laws.

Since p -> q is identical to ~p U q, the negation of p -> q is ~ ( ~p U q), which by de Morgan's Law is ~ ~p ^ ~q, or just p ^ ~q.

So the negation would ge 'loving you is wrong AND I want to be right.

COMMON ERROR AND NOTE: If loving you is wrong, then I want to be right.

INSTRUCTOR COMMENT:

The negation of a conditional can't be a conditional (a conditional is false in only one case so its negation would have to be false in three cases). **

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Self-critique (if necessary):

I’m not sure if my answer works or not because it means the opposite but the last of it still matches up with the beginning statement.

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Self-critique Rating:

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&#This also requires a self-critique.

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A little more information, which is implicit in the given solution:

The negation of a conditional is not a conditional.

The original statement was a conditional, and your answer for the negation is a conditional, so your answer can't be right.

As indicated in the given solution you have to express the original conditional as a disjunction. You can then apply deMorgan's rules to negate the disjunction.

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Self-critique (if necessary):

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Self-critique rating:

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See my notes regarding self-critique. Some of your solutions are not consistent with the given solutions, which you should self-critique in as much detail as possible.

I suggest you do your best to insert self-critiques into your original document and resubmit. Once I know what you do and do not understand in the given solution, I'll be glad to clarify points you don't fully understand.

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