Math 2.0

concept

Proposition

Summary

A proposition is a statement that is either true or false. In classical logic, each proposition has exactly one of the two truth values, true or false. For example, "2+2=42 + 2 = 4" is a true proposition, and "77 is even" is a false proposition. A question or a command is not a proposition, because it has no truth value.

Remarks

Letters such as pp, qq and rr usually denote propositions. An open sentence such as "x>3x > 3" is not a proposition until xx has a value. It is a predicate. The connectives negation, conjunction and disjunction make new propositions from given propositions.

Explanations

L1 human

A proposition is a sentence that you can mark with "true" or "false". "It rains in Paris now" is a proposition, because it is true or false at a given time. "Close the door" is not a proposition, because it is neither true nor false.

What this node needs for W2
  • edge defines in: at least one definition (0 of 1)
  • edge instance_of in: at least two examples (0 of 2)
  • edge not_instance_of in: at least one non-example (0 of 1)
  • edge specializes both: the more general notions and the special cases (0 of 1)

The writing levels say how complete the text of a node is. They do not measure its truth.

What depends on this

467 nodes use this node, directly or through other nodes.

Sources

  1. Web https://en.wikipedia.org/wiki/Proposition, lead section