Mystery Symbol: What Does a Big Inverted V Mean?

AI Thread Summary
The discussion centers on the meaning of a big inverted V symbol, with participants debating its interpretation in the context of deontic logic. One contributor suggests it represents "or," while another clarifies that it is not a disjunction and may signify a relation or function similar to sigma notation. The conversation highlights confusion over the symbol's role in quantification, particularly in relation to atomic formulas. Participants express the need for visual clarity, indicating that an image of the symbol would aid understanding. The inquiry remains open as the original poster plans to share an image for further clarification.
EvLer
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what does a big inverted V stand for? it's not "and" because it's used right in front of a literal (atomic formula) not sure if it's a quantifier... This is a paper discussing approach based on deontic logic that I am scanning through, but this sign i cannot figure out how to search online...
Does anybody know?
 
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EvLer said:
what does a big inverted V stand for? it's not "and" because it's used right in front of a literal (atomic formula) not sure if it's a quantifier... This is a paper discussing approach based on deontic logic that I am scanning through, but this sign i cannot figure out how to search online...
Does anybody know?

It means "or." http://en.wikipedia.org/wiki/Logical_disjunction
 
I understand a 'V' followed by a variable followed by a symbolic formula as an existential generalization and an 'inverted V' followed by a variable followed by a symbolic formula as a universal generalization. These symbols have to do with quantification.
 
well, no it is not a disjunction, that is why I said I was asking, plus it is INVERTED ... sounds more like it is a relation, although i think in certain other cases it is used like a "sigma"-notation, i.e. from 1 to n "and" certain literals together to form a formula. I guess i should have posted an image of it for clarity.
thanks though...
EDIT:
ok, I will post the image
 
I was reading documentation about the soundness and completeness of logic formal systems. Consider the following $$\vdash_S \phi$$ where ##S## is the proof-system making part the formal system and ##\phi## is a wff (well formed formula) of the formal language. Note the blank on left of the turnstile symbol ##\vdash_S##, as far as I can tell it actually represents the empty set. So what does it mean ? I guess it actually means ##\phi## is a theorem of the formal system, i.e. there is a...
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