Tagged Questions
2
votes
1answer
67 views
What is the difference between $Γ⊭Φ$ and $Γ⊭¬Φ$?
Did I understand this correctly?
$Γ⊨Φ$ ($Φ$ is considered true)
$Γ⊨¬Φ$ ($Φ$ is considered false)
$Γ⊭Φ$ ($Φ$ is considered neither true nor false)
$Γ⊭¬Φ$ ???
Please help me understand. How can ...
1
vote
1answer
83 views
Prove that $((p\lor q)\land(p\lor(\lnot q)))\rightarrow p$ is a tautology
Prove that $((p\lor q)\land(p\lor(\lnot q)))\rightarrow p$
Please could someone give me some feed back on this proof? Does it look correct?
= $\lnot ((p\lor q)\land(p\lor(\lnot q)))\lor p$
= $ ...
1
vote
0answers
163 views
proof of validity of tautology in first order logic
Every first-order logic formula which has a tautological shape in propositional logic is a valid formula. Will it be possible to give a formal proof for the above ? Thanks and Regards.
0
votes
1answer
35 views
How can I progress this derivation?
I'm learning propositional calculus in a discrete mathematics course.
I'm trying to kick the habit of using axioms like equations and now I'm a little stuck and could use a nudge.
Using a compact ...
2
votes
1answer
82 views
Does this proof using Novikov axiomatic propositional logic hold?
This question seems absolutely elementary but I'm having a hard time completing the proof, in fact I may have taken a bit of a left turn on it or I may be improperly applying axioms all together. ...
1
vote
2answers
128 views
Predicate Logic Argument Validity
My question is whether or not the following is a validly structured argument:
(P→T)→Q
Q → ¬Q
∴ P
I'm getting hung up on the Q→¬Q part by itself as a premise, it doesn't seem like that is ...
2
votes
3answers
200 views
Logical propositions, which one is true and how to write a short proof?
I am studying for an entrance exam. Now I am stuck on this question:
Suppose that P, Q are propositions such that "P or Q" is true. For
each proposition (1), (2) and (3) which of the following ...
