Predicate Logic Semantics - Models

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Logic & Philosophy

Logic & Philosophy

Күн бұрын

Пікірлер: 55
@DJCNK97
@DJCNK97 7 жыл бұрын
wow this is the best explanation on predicate logic on youtube.
@LogicPhilosophy
@LogicPhilosophy 7 жыл бұрын
Thanks. Hope it helped!
@philosophyversuslogic
@philosophyversuslogic 2 жыл бұрын
Someone has already said it, but I can positively confirm that - these cycle of videos are the best on the whole Internet. Absolutely!
@luiz8098
@luiz8098 3 жыл бұрын
I was clueless with the material my professor provided me with, but now I see the light! Thanks!
@LogicPhilosophy
@LogicPhilosophy 3 жыл бұрын
Glad I could help! Good luck!!!
@schalkzijlstra878
@schalkzijlstra878 3 жыл бұрын
Thanks for going slow and not rushing.
@LogicPhilosophy
@LogicPhilosophy 3 жыл бұрын
No problem 👍 Good luck in your logic journey!
@connorkianpour1077
@connorkianpour1077 4 жыл бұрын
Currently in grad school for philosophy, and have a final for logic coming up. I, like many others in my class, was already struggling with logic before the pandemic struck. Now that everything's been moved online and my professor has in no way adjusted his expectations for students with respect to command of the course material, I am struggling even more. These videos have been more helpful than I can possibly articulate. I feel like I am actually understanding predicate logic.
@LogicPhilosophy
@LogicPhilosophy 4 жыл бұрын
Thanks for your really kind comments about my videos! Would be interested to know what topics your graduate course covers. I've thought about making a series of videos on either metatheory, modal logic, or various nonclassical logics. Good luck!
@connorkianpour1077
@connorkianpour1077 4 жыл бұрын
@@LogicPhilosophy Truth tables, logical translations, propositional logic, predicate logic and identity, and some modal logic. We do a bit of metatheory as well. The way you explain concepts is extremely helpful; please keep doing this!
@rss2729
@rss2729 Жыл бұрын
😅 BL
@rss2729
@rss2729 Жыл бұрын
Bbbb
@hannahcora5939
@hannahcora5939 6 жыл бұрын
this is 10x better than my prof. pls keep making more videos about computability and logic
@LogicPhilosophy
@LogicPhilosophy 4 жыл бұрын
I appreciate this! I'm hoping to do more in the spring of 2021. Some on modal logic, Russell's theory of definite descriptions, and maybe some stuff on theories of computation. But this is hopeful! Best wishes!
@Peepeeloo-pee
@Peepeeloo-pee 3 жыл бұрын
you know how to drive message home...Good job !
@agnivobanerjee2864
@agnivobanerjee2864 4 жыл бұрын
please do on algebraic or fuzzy logic too :)) great work!
@VietnamSteven
@VietnamSteven 2 жыл бұрын
Thanks for this fantastic video!
@s.o.peprah7114
@s.o.peprah7114 4 жыл бұрын
This is amazing and so good. Keep it up!
@LogicPhilosophy
@LogicPhilosophy 4 жыл бұрын
Thanks!
@EduardoMengesMattje
@EduardoMengesMattje 2 жыл бұрын
Very good
@LogicPhilosophy
@LogicPhilosophy 2 жыл бұрын
Thanks!
@obrown4331
@obrown4331 6 жыл бұрын
Thank you so much you saved me just before my exam!!!
@LogicPhilosophy
@LogicPhilosophy 6 жыл бұрын
+O Brown no problem. Good luck!
@PETERKENTISH
@PETERKENTISH 7 жыл бұрын
Very helpful! exam tomorrow :)
@LogicPhilosophy
@LogicPhilosophy 7 жыл бұрын
+Peter Kentish thanks, and good luck!
@PETERKENTISH
@PETERKENTISH 7 жыл бұрын
Thanks, I dont suppose you could help me with a question I have? I would have to send a screenshot which i dont think i can do here
@francescovaglienti2827
@francescovaglienti2827 5 жыл бұрын
This is incredibly clear and useful thank you so much.
@LogicPhilosophy
@LogicPhilosophy 4 жыл бұрын
you are very welcome!
@monoman4083
@monoman4083 6 жыл бұрын
nice and clear so far, thx..
@LogicPhilosophy
@LogicPhilosophy 6 жыл бұрын
Appreciate it! Taking a class?
@jonz9813
@jonz9813 4 жыл бұрын
nice tutorial! I have a question about the interpretation function. In the example that name a is interpreted to one, aka I(a) = 1, what is "a" and "1" in terms of the set of symbols from your first tutorial? Are they both names? Does this mean an interpretation function is a map closed under domain?
@LogicPhilosophy
@LogicPhilosophy 4 жыл бұрын
Here "a" is a name in the language of predicate logic where "1" would simply be the integer 1 (I'm using it as a dummy object here so "1" could be whatever item you want it to be from the items you want to talk about. I could have just as easily picked people: Jon, Jill, Liz, et alia.). The basic idea is that the name "a" refers to the number 1 just as a proper name "David" refers to the person David. I know that sometimes people distinguish maps from functions (and I don't know enough to appreciate the difference).
@jonz9813
@jonz9813 4 жыл бұрын
Logic & Philosophy thank you very much! Love your tutorials. Super helpful
@GustavoOliveira-gp6nr
@GustavoOliveira-gp6nr 4 жыл бұрын
It makes more sense if you imagine "a" as a physical symbol to represent an abstract idea and "1" is the idea. Actually while writing this very text, i am using the indoarabic character "1" to represent an idea, which is the idea of the integer number greater than zero and less than two. Imagine you are solving an equation and you come up with a solution "a=b". That means that "a" and "b" are symbols that stand for the same mathematical object, which is unique. That is what he meant in the video when he said two symbols can stand for the same mathematical object.
@gingerbeardworkouts2955
@gingerbeardworkouts2955 5 жыл бұрын
Great explanations ! Thanks
@LogicPhilosophy
@LogicPhilosophy 5 жыл бұрын
Appreciate it!
@daffmaul9813
@daffmaul9813 7 жыл бұрын
First video I have seen from you and I think its damn good
@LogicPhilosophy
@LogicPhilosophy 4 жыл бұрын
Awesome! Appreciate the feedback.
@theodore8178
@theodore8178 5 жыл бұрын
I like the empty domain. Anything I want to say about the elements is true. And proofs are much faster.
@LogicPhilosophy
@LogicPhilosophy 5 жыл бұрын
Yes. Isn't that strange? It's true if you are saying "All men are mortal" when there are no men, but you run into issues if you say something like "there exists a man" since the truth of that wff would imply the exists a man.
@theodore8178
@theodore8178 5 жыл бұрын
@@LogicPhilosophy right
@keivwangz
@keivwangz 7 жыл бұрын
you just saved my life lol. amazing videos!!
@LogicPhilosophy
@LogicPhilosophy 7 жыл бұрын
+Austin Genovaczeck your welcome
@dvendator
@dvendator 5 жыл бұрын
this is great!!! Thankyou
@LogicPhilosophy
@LogicPhilosophy 4 жыл бұрын
You are welcome. Best wishes!
@scovila
@scovila 6 жыл бұрын
Thanks!!
@LogicPhilosophy
@LogicPhilosophy 6 жыл бұрын
Ur welcome
@viktorbonev5654
@viktorbonev5654 5 жыл бұрын
RESPECT!
@LogicPhilosophy
@LogicPhilosophy 4 жыл бұрын
Respect right back to you!
@diegoaraujo4141
@diegoaraujo4141 6 жыл бұрын
("_" means subscript, quantifiers are specified in brackets) Hi David, I am having trouble with an unsure conclusion that i share with Gamut's Logic, Language and Meaning. Chapter 3, exercise 9: Prove that ( [for all]x(fi) → [t/x](fi) ) is universally valid (using valuations under a model M and an assignment function g). The demonstration that the book gives (pp. 249) goes like this. "Suppose V_M,g([for all]x(fi)) = 1. It is to be proven that V_M,g([t/x](fi)) = I. That V_M,g([for all]x(fi)) = I means that for all d [in] D, V_M,g((fi)) = 1. In particu- lar, [[t]]_M,g is such an element of D. From this it follows that V_M,g([t/x](fi)) = 1 (strictly, this should be proven with induction on the length of (fi))." My concern is: from where does it comes the assumption that every name or variable "t" member of L is defined for the interpretation function I? Couldn't just exist a term t such that I(t) = undefined? In such a case, I(t) [not member of] D, where it follows that there is a counter-example to the universal validity of the initial formula. Nevertheless, great videos and promulgation of logic to youtube :D
@LogicPhilosophy
@LogicPhilosophy 6 жыл бұрын
So your question concerns an earlier part of Gamut's book where they define the Interpretation and variable-assignment functions. While there is no guarantee that everything in the domain has a term that picks it out, your pointing out how can they assume that every name picks out an element in the domain. It is pretty standard for logic textbooks to make this assumption and when they do, it is nothing more than an idealization (or just pure stipulation). I imagine there is a debate over it but where you would look to see if anyone has argued for this is the literature on Free Logic or anything on empty names or non-referring names. So, yes, it could be the case that there are terms (e.g. names) that are undefined for certain models. As an example, suppose our domain contains only living physical objects found here on planet Earth in 2018, the name "Pegasus" would thus be non-referring or undefined for the interpretation function. In short (but I'd have to check on this), I would imagine that a logic that doesn't make this assumption (aka free logic) would not regard the formula in question as being universally true. That is, even if we assume that (Ax)(fi)=T, it isn't the case that [t/x](fi)=T for all terms (t).
@ManInTheTimeMachine
@ManInTheTimeMachine 3 жыл бұрын
giving me mad anxiety bro, but thanks
@LogicPhilosophy
@LogicPhilosophy 3 жыл бұрын
Hope it ain't me that is giving you that stress. Good luck!
@Whositlover
@Whositlover 5 жыл бұрын
why to logic professors have such hard times teaching it...
@LogicPhilosophy
@LogicPhilosophy 5 жыл бұрын
Not sure about the question but sometimes the discussion of models isn't terribly clear in introductory logic textbooks. There are some exceptions though! Hope the video helped. Good luck!
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