LARA

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Simple QE for Dense Linear Orders

Example of dense linear order: rational numbers with less-than relation. (It works in the same way for real numbers with less-than relation.)

Theory of Dense Linear Orders

Language ${\cal L} = \{ < \}$. Atomic formulas are of two forms:

  • $x=y$
  • $x < y$

Literals are either atomic formulas or their negations.

Formulas $T$ are the formulas that are closed formulas that are true in the structure $(\mathbb{Q},<)$ or rational numbers.

Normal form of Formulas

We have seen that it suffices to eliminate quantifiers from conjunctions of literals.

Can we assume that literals are of a special form?

Example: simplify the formula \[

 x < y\ \land\ \lnot (y < z) \ \land\ (x \neq z)

\]

Quantifier Elimination Step