"What is the difference between
⊨
(semantic consequence) and
⊢
(syntactic consequence)?" was a question that has been posted, but I am wanting a more specific answer. For example, this video explains what a syntactic consequence is. After watching this video, it is obvious that we say
p
⊢q
when p->q is a tautology where p and q are given propositions forming the tautology. What is an easy way to explain what a semantic consequence is? I have been obsessed looking at this question for awhile. Any help would be greatly appreciated.
[Math] Semantic Consequence Definition
logicpropositional-calculus
Best Answer
$\vDash$ means: logical consequence.
The general definition of it is:
In the context of propositional logic, this means that:
Trivial example (where $\Gamma$ has only one formula):
A truth assignment $v$ satisfy $p \land q$ only if $v(p)=v(q)=$ T.
Thus, every truth assignment $v$ that satisfy every formulas in $\Gamma$, i.e. that satisfy $p \land q$, satisfy also $p$.
$\Gamma \vdash_{\mathcal S} \varphi$, instead, means that $\varphi$ is derivable (in the proof system $\mathcal S$) from the set of assumptions $\Gamma$.