To install click the Add extension button. That's it.

The source code for the WIKI 2 extension is being checked by specialists of the Mozilla Foundation, Google, and Apple. You could also do it yourself at any point in time.

4,5
Kelly Slayton
Congratulations on this excellent venture… what a great idea!
Alexander Grigorievskiy
I use WIKI 2 every day and almost forgot how the original Wikipedia looks like.
Live Statistics
English Articles
Improved in 24 Hours
Added in 24 Hours
Languages
Recent
Show all languages
What we do. Every page goes through several hundred of perfecting techniques; in live mode. Quite the same Wikipedia. Just better.
.
Leo
Newton
Brights
Milds

# Logical constant

In logic, a logical constant or constant symbol of a language ${\displaystyle {\mathcal {L}}}$ is a symbol that has the same semantic value under every interpretation of ${\displaystyle {\mathcal {L}}}$. Two important types of logical constants are logical connectives and quantifiers. The equality predicate (usually written '=') is also treated as a logical constant in many systems of logic.

One of the fundamental questions in the philosophy of logic is "What is a logical constant?";[1] that is, what special feature of certain constants makes them logical in nature?[2]

Some symbols that are commonly treated as logical constants are:

Symbol Meaning in English
T "true"
F, ⊥ "false"
¬ "not"
"and"
"or"
"implies", "if...then"
"for all"
"there exists", "for some"
= "equals"
${\displaystyle \Box }$ "necessarily"
${\displaystyle \Diamond }$ "possibly"

Many of these logical constants are sometimes denoted by alternate symbols (for instance, the use of the symbol "&" rather than "∧" to denote the logical and).

Defining logical constants is a major part of the work of Gottlob Frege and Bertrand Russell. Russell returned to the subject of logical constants in the preface to the second edition (1937) of The Principles of Mathematics noting that logic becomes linguistic: "If we are to say anything definite about them, [they] must be treated as part of the language, not as part of what the language speaks about."[3] The text of this book uses relations R, their converses and complements as primitive notions, also taken as logical constants in the form aRb.

• 1/5
Views:
36 453
1 845
2 099
12 273
15 088
• Logic & Language - intro to logic; constants & variables (Logic 1 of 5)
• +2 LOGIC, SYMBOLIC LOGIC, TRUTH FUNCION, logical constants, propositional variable,E-Teaching ODISHA
• Joseph Abrahamson on "On the Meanings of the Logical Constants"
• 4 2 4 2 Clausal Form 5 min
• PLC Programming Software: EATON easySoft (Part 2 of 2)