Lecture "Programming languages", exercise 2 about 2018-2019 HOT 17 OPEN

Mmmm.. I wonder if I got this wrong:

("spam" not in "spa span sparql") --> is "spam" not in "spa span sparql"? --> No = True

("egg" > "span") --> is "egg" bigger than "span" (is egg alphabetically bigger than span?) --> No = False

True and not (False)

True and True

True

from 2018-2019.

“Spam” not in “spa span sparql” = T

Not (“egg”>”span”)= F

T and F = F

from 2018-2019.

"spam" not in "spa span sparql" = True
and
not ("egg" > "span") = True
True and True = True

Note: I agree with @delfimpandiani: if "a string S1 is less than another string S2 if the former one precedes the latter one according to a pure alphabetic order" (Table 2, Programming languages lecture notes), I suppose that a string is greater than another string if the former follows the latter in alphabetical order, therefore "egg" > "span" = False because "egg" does not follow "span" in the alphabet.

from 2018-2019.

"spam" not in "spa span sparql" and not ("egg" > "span")

"spam" not in "spa span sparql" = True
not ("egg" > "span") = not False = True

True and True = True

from 2018-2019.

"spam" not in "spa span sparql" = True
("egg" > "span") = False --- not False = True
According to the Boolean value;
True and True = True

from 2018-2019.

"spam" not in "spa span sparql" and not ("egg" > "span")
True and not (False)
True and True
True

from 2018-2019.

from 2018-2019.

"spam" not in "spa span sparql" and not ("egg">"span")
T and not F
T and t
True

from 2018-2019.

"spam" not in "spa span sparql" and not ("egg" > "span")
True and not (False)
True and True
True

from 2018-2019.

"spam" not in "spa span sparql" and not ("egg" > "span")

• I phase: brackets and first not don't influence each other so I can do them at the same time. Spam Is not in the string "spa span sparql" so "not" will return True. "Egg" is located before "span" so the operator "&gt" will return False (egg is "less" than "span")
  Result:
  True and not False

• II phase: I have to do "not" before "and"
  Result:
  True and True

• III phase: now I can do the last operation "And"
  result: True

from 2018-2019.

"spam" not in "spa span sparql" and not ("egg" > "span")
"spam" not in "spa span sparql" and not (False)
True and True
True

Again, we need to execute the operation contained in round brackets "egg" > "span". Alphabetically, e is not bigger than s (that is, it comes first in order) so the output is False. Then we resolve not operators and, finally, the and operator.

from 2018-2019.

What is the boolean value of ​"spam" not in "spa span sparql" and not ("egg" > "span")​?

"spam" not in "spa span sparql" and not (False) ​ >> "egg" should be less than "span"
true and not false
true

from 2018-2019.

Applied with strings, the logical operator > ("egg" > "span") uses the alphabetic order for the operation, e.g. "a" < "b" is true, because the letter "a" is listed before "b" in the alphabetic order. Based on this rule, the computation "egg" > "span" is false.

"spam" not in "spa span sparql" and not ("egg" > "span")
true and not(false)
true and true
true

from 2018-2019.

"spam" not in "spa span sparql" and not ("egg" > "span")

"spam" not in "spa span sparql" = True
not ("egg" > "span") = not (False)
True and not (False) = True and True
=> True

from 2018-2019.

"spam" not in "spa span sparql" and not ("egg" > "span")

"spam" not in "spa span sparql" --> true
("egg" > "span") --> false

true and not (false)
true and true
true

from 2018-2019.

Question

In the absence of round brackets, string operations have priority over boolean operations right? I was just wondering since "spam" not in "spa span sparql" is not between round brackets but ("egg" > "span") is. It does completely make sense to me if it works like this, otherwise you might have boolean operators operating on strings rather than booleans. If this is correct this would mean that the round brackets around ("egg" > "span") are redundant. Any body could confirm this by commenting the hooray on my question?

from 2018-2019.

@HiImBono

Answering your question, indeed all the comparisons will be executed before any other boolean operation.

from 2018-2019.