Monday, March 02, 2020

Logic examples for your Discrete Math class

(I injured my hand about a month ago so I have had a hard time typing. That is why
I have not blogged for a while. I'm better now but still slow. This is a post I prepared
a while back.)

Here are some examples of English and logic for your discrete math class. Or for mine anyway.

1) A computer programmer leaves work and heads for home. Being the good spouse that he is, he calls  his partner and asks if there's anything that needs to be picked up on the way.

Yes, a gallon of milk and, oh, if they have eggs, get a dozen.

Later he arrives home and stumbles into the kitchen burdened with a dozen gallons of milk. His partner  perplexed, asks him ``why in the world did you buy 12 gallons of milk?''

What did he answer?

When I told this to my class one student said that he should answer:

                                                      I love you too Darling

while that is always a good thing to tell Darling, it is not the answer I had in mind.

The  answer is  here.

2) I saw a headline:

                                                  Rise in faux-incest porn alarming

Give two different interpretations of this sentence. (Note- One you might agree with, the other you will likely disagree with.)

My answer is  here

3) Recently someone was describing what I work on to someone else and he said the following wonderfully ambiguous sentence

                           Bill works on puzzles and games. He also work on cake cutting, to be fair.

Give two different interpretations of this sentence.  My answer is here

4) A common saying is

                           All that glitters is not gold

What does this mean literally? What did they really mean to say? My answer is here.

(I had originally thought this was a quote from the Led Zeppelin song Stairway to Heaven;
however, an astute reader left a comment reminding me that, in that song, they actually
say that there is a lady who believes All that Glitters is Gold. The song implies that she is incorrect, so really
NOT(All that Glitters is Gold) which means (exists x)[x glitters but x is not gold] which actually
IS what they meant to say. Yeah!)

5)When the chess player Bobby Fisher died I saw in one article about him the sentence

                                Bobby Fisher was a terrible anti-semite.

This can be interpreted two ways. What are they? Which one did the writer probably mean? My answer is here

6) When Donald Trump broke the Nuclear Treaty with Iran he said

                              Iran is the worse enabler of terrorist in the mideast

This can be interpreted two ways. What are they? Which one did Trump mean? My answer is here.

7) I saw the headline (see here)

There was actually good news in the War on Women in 2019, news we have to build on in 2020.

This can be interepreted in two ways. This one I leave to you, or read the article.


  1. FYI The lyric from "Stairway to Heaven" is:

    There's a lady who's sure
    All that glitters is gold
    And she's buying a stairway to heaven

  2. The "all that glitters is not gold" line is a set phrase in modern English. I think it uses an archaic English construction where it could literally mean either "for all x, if x glitters, x is not gold" or "there exists x that glitters and is not gold". Wikipedia says that variants of the phrase were in use before Chaucer and the modern form is a variant of a Shakespeare quote that used the now-rare word "glisters" instead.

  3. #2 is not ambiguous; the hyphen is there for a reason. (I.e., "faux-incest porn" and "faux incest porn" mean different things that seem to correspond roughly to your first and second interpretations.)

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  5. These are all valid logic examples. However I certainly don't consider many of them appropriate for a Discrete Math (or any) class, because of the context/content which unfortunately many in our community are not sensitive about. I would say only #1, #3, #4 are OK choices.