The Logic Course Adventure channel is devoted to logic instruction of all kinds. Check out the playlists, which group videos by textbook!
Currently we have playlists for two formal logic textbooks: (1) our own book, the Logic Course Adventure, and (2) LPL, Language, Proof and Logic. If you end up here for a different textbook, let us know and we'll try to add support for it.
I am literally doing 2.24 right now, and actually Ana Con is not only insufficient to just auto-prove this (I tried "cheating" as you say after watching your vide and just citing everything) -- while each step checks out, the goal will not satisfy, and the note when hovering over the X at the bottom says, "You may not use the Ana Con rule to satisfy this goal". I first tried it with the exact same steps as yours and could only get that result, so I went to searching online for any answer and that's how I found your video. I don't think Ana Con is "cheating" necessarily, not unless you choose to use it that way. One could be super lazy, sure, but the Grade Grinder does report Ana Con usage to your instructors! Up to the individual I guess if they just don't want to bother thinking through the exercises at all, and just try Ana Con on everything? But that feels like more work that necessary, I would assume you would have to think a LITTLE to even want to try it out? I think it makes sense that they would need to be able to give you a way to reason within the blocks' world language, and obviously the Ident and Elim rules just aren't enough for that. I think they are trying to show how expanding from pure logic into natural language - even a very limited First Order Language like blocks world - helps you learn to reason, since presumably the ultimate goal is not just to work on trivial pure logic Fitch exercises forever but to be able to discern valid and invalid arguments in the real world. In any case, it looks like they made a software update or something, so maybe they heard your cries! :) Also, your video helped me to realize I haven't done anything wrong in terms of my proof for this exercise. The steps ARE correct. They have updated something in the nature of how Ana Con works for satisfying goal statements, I think. I'm just going to move on in working my way through this textbook.
Total bullshits. How can you assert that \aleph_0 + 1 = \aleph_0 if the procedure of comparison never can be finished? Algorithm without terminal state doesn't prove anything. :-)
You may not have many views, but I can assure you that all those views are from people who were stuck and especially searched up your video. You've helped almost 300 people now. Thank you
Love how you explain the logic, but the long list does not help to find what we need easily.. perhaps you can add each course into sublist. But besides that, THANK you very much
How would you go about proving (Av~B)->(A->B) with no premises? I'm taking intro to formal logic and we're using a different textbook which doesn't explain things well at all.
Tell your instructor about the LCA textbook at logiccourse.com! Here's how: since your goal is a wide-scope conditional, you assume the antecedent, Av~B, in a subproof, and try to get to the consequent, A->B. Now your new goal is the consequent: A->B, and since that is a wide-scope conditional, you again start another subproof assuming the antecedent, A, trying to get to B. We discuss these ideas in several videos, like LCA Video 51 Arrow Intro ->Intro ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ySXQ-Lcii_w.html .
