Elysian Shadows

I am taking a discrete structures class but I just cant learn how truth tables work. Ill just leave this here and hope someone can help me.

feel free to download the slides we have to study.(I deleted The link because im afraid ill get in trouble for linking to college materials) zomg free I dont know if its just me but it takes a long time to load the page.

PDF's not liking me.
1 and 1 is 1
1 and 0 is 0
0 and 1 is 0
0 and 0 is 0

Truth table:
a__|__b__|__a AND b [a and b must be 1 to get 1]
1__|__1__|__1
1__|__0__|__0
0__|__1__|__0
0__|__0__|__0

1 or 1 is 1
1 or 0 is 1
0 or 1 is 1
0 or 0 is 0

Truth table:
a__|__b__|__a OR b [a or b or both are 1 to get 1]
1__|__1__|__1
1__|__0__|__1
0__|__1__|__1
0__|__0__|__0

a implies b is logically equivalent to "(NOT a) OR b" -- harder to read this way, but easier to compute.
a__|__b__|__!a_|__!a OR b
1__|__1__|__0__|__1
1__|__0__|__0__|__0
0__|__1__|__1__|__1
0__|__0__|__1__|__1

You find truth tables difficult? :/

I guess you're a freshman for a reason.


/me slacking off in senior level classes.

the reason the pdf takes so long is because is like 100 megs in slides. I deleted the link because im pretty sure they have google analytics then theyll know ive been linking to the class site.

Just think of the truth table in a straight forward manner and it will make sense.

Two basic examples:

AND asks for both propositional variables to be true, in order for the conclusion to be true. So:
T AND T = T
T AND F = F
F AND T = F
F AND F = F

OR only asks for one of the two to be true, in order for the conclusion to be true. So:
T OR T = T
T OR F = T
F OR T = T
F OR F = F

It could get a little tricky when you throw other logical connectives into the mix; eg implications,
equivalences, and then apply these to logical proofs, while keeping track of their rules of inference, etc.
Not to mention quantifications. You have some work to do Levio

Probably one of the only person who can answer this is Marauder (CS major), but I was curious to know if you any guys can figure out the name of this rule of inference:

p -> q
q -> r
_____
p -> r

Hint: its a *gism*

Intro to Discrete Structures? Isn't that CS214? You a sophomore?

I took it, didn't study or do my homework, fucked up the first test, then dropped a few semesters ago. I made some bad choices, mostly due to being totally in love.

Truth tables are so much cooler in circuits. They aren't completely abstract. You can see "oh damn, my shit outputs a positive voltage here." Though I suppose you could write the equivalent in code and say "oh damn, this condition evaluated to true." But hey, I'm CPE, I totally do both.

GyroVorbis wrote:Intro to Discrete Structures? Isn't that CS214? You a sophomore?

I took it, didn't study or do my homework, fucked up the first test, then dropped a few semesters ago. I made some bad choices, mostly due to being totally in love.

Truth tables are so much cooler in circuits. They aren't completely abstract. You can see "oh damn, my shit outputs a positive voltage here." Though I suppose you could write the equivalent in code and say "oh damn, this condition evaluated to true." But hey, I'm CPE, I totally do both.

well my advisor who helps me pick my schedule is also one of the main comp science proffessors so when I told him that my algebra teacher advised me to take take a algebra prerequisite he said i should just get some tutoring and take it next year. So he signed a corequisite paper that lets me take the class my freshman year.

Levio91 wrote:

GyroVorbis wrote:Intro to Discrete Structures? Isn't that CS214? You a sophomore?

I took it, didn't study or do my homework, fucked up the first test, then dropped a few semesters ago. I made some bad choices, mostly due to being totally in love.

Truth tables are so much cooler in circuits. They aren't completely abstract. You can see "oh damn, my shit outputs a positive voltage here." Though I suppose you could write the equivalent in code and say "oh damn, this condition evaluated to true." But hey, I'm CPE, I totally do both.

well my advisor who helps me pick my schedule is also one of the main comp science proffessors so when I told him that my algebra teacher advised me to take take a algebra prerequisite he said i should just get some tutoring and take it next year. So he signed a corequisite paper that lets me take the class my freshman year.

Wow, I think Calclulus B is probably a prereq at my school.

GyroVorbis wrote:

Levio91 wrote:

GyroVorbis wrote:Intro to Discrete Structures? Isn't that CS214? You a sophomore?

I took it, didn't study or do my homework, fucked up the first test, then dropped a few semesters ago. I made some bad choices, mostly due to being totally in love.

Truth tables are so much cooler in circuits. They aren't completely abstract. You can see "oh damn, my shit outputs a positive voltage here." Though I suppose you could write the equivalent in code and say "oh damn, this condition evaluated to true." But hey, I'm CPE, I totally do both.

well my advisor who helps me pick my schedule is also one of the main comp science proffessors so when I told him that my algebra teacher advised me to take take a algebra prerequisite he said i should just get some tutoring and take it next year. So he signed a corequisite paper that lets me take the class my freshman year.

Wow, I think Calclulus B is probably a prereq at my school.

Isnt calculus harder than algebra? Math is my weak link.

About 3 classes harder. Aka "way the hell harder."

If you aren't 100% on your algebra it'll bite you in your calculus.

Calc B is a prereq for getting into your school Falco? Algebra II is my highest level of math, only reason I didn't take Trig or Calc is because I slacked on homework.

I had a test.... It was really easy there were over 25 questions and i only got 3 wrong... I got those wrong because I didnt know what the upside down u looking symbol mmeans ( I still dont ) but I overstudied!!!!!!!!! I know too much!

Now that im caught up with the rest of the class its actually one of the classes I enjoy.

intersection

A and B are sets
A = {1, 2, 3, {7, 8}, {9, 0} }
B = {3, 7, {9, 0} }

A intersect B is
{3, {9, 0} }

A simpler example:
C and D are sets:

C = {1, 2, 3, 4, 5, 6, 7, 8, 9}
D = {7, 2}
C intersect D is
{2, 7}