Sahlqvist Formula - Definition

Definition

Sahlqvist formulas are built up from implications, where the consequent is positive and the antecedent is of a restricted form.

  • A boxed atom is a propositional atom preceded by a number (possibly 0) of boxes, i.e. a formula of the form (often abbreviated as for ).
  • A Sahlqvist antecedent is a formula constructed using ∧, ∨, and from boxed atoms, and negative formulas (including the constants ⊥, ⊤).
  • A Sahlqvist implication is a formula AB, where A is a Sahlqvist antecedent, and B is a positive formula.
  • A Sahlqvist formula is constructed from Sahlqvist implications using ∧ and (unrestricted), and using ∨ on formulas with no common variables.

Read more about this topic:  Sahlqvist Formula

Famous quotes containing the word definition:

    The very definition of the real becomes: that of which it is possible to give an equivalent reproduction.... The real is not only what can be reproduced, but that which is always already reproduced. The hyperreal.
    Jean Baudrillard (b. 1929)

    The physicians say, they are not materialists; but they are:MSpirit is matter reduced to an extreme thinness: O so thin!—But the definition of spiritual should be, that which is its own evidence. What notions do they attach to love! what to religion! One would not willingly pronounce these words in their hearing, and give them the occasion to profane them.
    Ralph Waldo Emerson (1803–1882)

    It is very hard to give a just definition of love. The most we can say of it is this: that in the soul, it is a desire to rule; in the spirit, it is a sympathy; and in the body, it is but a hidden and subtle desire to possess—after many mysteries—what one loves.
    François, Duc De La Rochefoucauld (1613–1680)