7.4 Rules of Replacement II

[@priyanshifauzdar9007]

The fact that this video came out about eight years ago and is still helping students like me understand Logic is honestly so amazing. I have always been extremely scared of logic but always managed to get through the exams but this is the first time ever that I am actually enjoying logic and I am about to finish the entire series and I couldn't be happier. Thank you. This is so beautiful. I never knew Logic could be fun so, honestly, thank you.

[@brendasandoval3099]

Your videos saved my life. I have a midterm today and i've been binge watching your videos and I learn everything in just a few hours than I do when sitting in class. Thank you.

[@karentroester148]

Thanks so much for your videos. You explain things so much better than my instructor online.

[@emperorjustice]

These videos have been extremely helpful. 🙏🏾

[@risstobarbosa6901]

this man has saved my life

[@beatricecastaneda685]

I was lost here too but, in H.S. it means p>q, q>r, then p>r. He combined Lines 2 and 6 because "F" is "q", you cannot assume that (~g and g) is "q" because it is not the same in both lines. The only way you can connect the two lines is with something in common which is "F" :) So when you compare to the H.S. pattern, it's actually ~G>F, F>G to get ~G>G. :) Hope this helps. :D

[@Zen-lz1hc]

Like :) I do enjoy even videos over 50min. Great lectures.

[@laurelweaver-serrano4935]

Thanks so much for your videos! You have helped make logic more LOGICAL!

[@pranit13a]

thank u soo much..this videos hav made a real difference ..you are an outstanding teacher..keep it up..god bless u..thank u so so much..

[@BWVidventures]

thankyou!!! tomorrow is my midterm exaaam... wish me luck to remember everything and to pass :')

[@PhilosophicalTechne]

You can do it! Best of luck.

[@BWVidventures]

@@PhilosophicalTechne Thank you Sir! 🙏😊

[@BWVidventures]

I am now a 2nd year in college. we have this subject again in Discrete Math 2. Haha. im here again for my hw and prelim on mondayyy

[@cyrylbarlam3375]

thanks! this is very helpful!

[@brianho6625]

Transposition p ﬤ q ≡ - q ﬤ - p If it rains (p), then floor wet (q) ≡ if floor not wet (-q), then it does not rain (-p). If father (p) exists, then son exists (q) ≡ If son not exists (-q), then father not exists (-p). What is wrong with above substitution into the transposition function for father and son case?

[@arrrland]

Dude, thank you so much.

[@TheMorhaGroup]

I do not see how the exportation rule holds. Because, the left-hand side tells us R is a direct implication of P, while the right-hand side tells us that R is a hypothetical implication of P, through Q. A hypothetical implication being, an implication brought about from a hypothetical syllogism. Even with real-world examples one can see the logic of exportation does not hold, as one can poor water and wet the road, without the rain, but both the rain and pouring water, imply the road will be wet, but neither poring water nor rain share any such implication on each other, as the right hand claims. Where the pouring of water, implies the rain, which implies the ground being wet.

[@MagicianMarcus]

Quick question. Can (A>A) > (Z>Z) be viewed as a substitution instance of P>(Q>R) so that the former becomes [(A*A)> (Z>Z)] through exportation?

[@AbdulRaheem-rb3kx]

I need answers of Exercise

[@attorney1100]

Hi Professor Thorsby. What Text you use?

[@lemonhead1256]

hurley

[@kelbyreyes3599]

is there a limit of using simplification?

[@eleonoraciyinta]

N>D /N>(S>D) I cannot for the life of me figure out how to do this exercise. Someone help me

[@robobrain10000]

These 2nd set of rules of replacement are ridiculously hard to keep track of. The logic is there, but it isn't as intuitive.

[@francescopiazza4882]

A bit difficult, but a great lesso n!

[@buffaloSoldier519]

This confused the hell out of me because some of my rules have different names...

[@universalchesslyfe3813]

how would you solve 1. (H -> H) -> G // G

[@markthorsby2875]

This problem can be solved using an indirect proof. If we assume the negation of the conclusion, ~G, the premise can be shown, using the rules of replacement, to result in a contradiction. Therefore, our assumption must be false. Since ~G is false, then G must be true logically.

[@universalchesslyfe3813]

Which rules of replacement? Is it possible to use the rules of inference?

[@universalchesslyfe3813]

How would I use the rules of replacement to solve this?

[@universalchesslyfe3813]

I appreciate your help. I was getting a little confused on how to prove this argument valid. I'm trying to follow Hurley's model of Conditional Proof or the Rules of Replacement. Being one line just threw me off . Thanks again

[@beatricecastaneda685]

I mean lines 1 and 6 :) not 2 and 6 :D