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1d
comment Inference in First Order Logic
Maybe you would do better to edit the question and show your work clausifying the assumptions. Do you know which equivalences come as useful here? What logical equivalences do you know that change statements into formulas that only have negation symbols, letters, and disjunction symbols?
1d
comment Inference in First Order Logic
So that makes each statement into an abbreviation of a clause. It might help to explicitly clausify every assumption and all 4 possible conclusions.
Aug
25
comment Inference in First Order Logic
There are no rules of inference here. Consequently, you cannot infer anything from those assumptions. So, you can't infer a), nor b), nor c), nor d)
Aug
23
answered Solve $\log_4 ( 16^{100})$
Aug
22
answered Is $'' \sum_{n = 1}^{\infty} (-1)^n \; \text{is a real number}''$ an invalid statement or a false proposition?
Aug
22
comment Is $'' \sum_{n = 1}^{\infty} (-1)^n \; \text{is a real number}''$ an invalid statement or a false proposition?
@DanielV Who are you talking to?
Aug
22
comment Is $'' \sum_{n = 1}^{\infty} (-1)^n \; \text{is a real number}''$ an invalid statement or a false proposition?
@Ishfaaq You're right that what I wrote before is incorrect. That said, the "sum" here is the set {-1, 0}. The sequence of partial sums here goes (-1, 0, -1, 0, ...). All terms of the sequence of all partial sums get infinitely close to one member of the set {-1, 0}. I also think that definition of a sum that you've used a special case of a more general definition.
Aug
9
answered Explaining multiplication of fractions
Aug
9
comment What is the Equivalent formula of $((a\to b) \to ((a \to c) \to (c \to a)))$
How did you eliminate ¬b?
Aug
8
awarded  Popular Question
Aug
7
answered Is there a way to tell how many different ways you can prove a theorem?
Aug
7
comment Is there a way to tell how many different ways you can prove a theorem?
I don't see how A⟹P⟹Q⟹B is the same proof as A⟹P⟹B. I'm not even sure what A⟹P⟹Q⟹B means (⟹ doesn't associate).
Aug
6
comment Why is the assumption needed in this conditional introduction?
@GitGud I think Malnormalulo did confuse syntax with semantics. However, the confusion, in this case, has its uses. It does hold that you can get to "P→Q" from Q in a single step in say formal systems where condensed detachment lies around as a permissible rule of inference, and (α→(β→α)) is a thesis (either an axiom or a theorem). There exist many axiomatic proofs where this comes in handy.
Aug
6
answered Why is the assumption needed in this conditional introduction?
Aug
6
comment Unique decomposition of wffs when left and right parentheses are indistinguishable
Your algorithm implies that the third parenthesis in |α∨|β∧γ|| is a left parenthesis, since the third "|" is preceded by ∧. You would do better to say "immediately preceded by".
Aug
4
answered Is it true that $f(a,b)=f(a,c)$ whenever $b=c$?
Aug
3
accepted Can There Get Found Single Axioms for Some Subsystems of Propositional Calculus?
Jul
31
comment Creating Truth tables
What are the possible truth-values?
Jul
29
answered Examples of “Non-Logical Theorems” Proven by Logic
Jul
22
answered Where's the problem with a false “proof”: $\;1^0 = 1^2 \overset{?}\implies 0 = 2$