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Tarski: quantifier elimination and decidability of elementary real algebra

Contribution grade

Mathematical logic and real algebra · Exact theorem and reusable mathematical method

Reference score420,000Provisional editorial estimate of this exact contribution; its grade is assessed separately.

What changed

Tarski gave an effective procedure converting first-order real-algebra formulas built from polynomial equations, inequalities and logical quantifiers into equivalent quantifier-free formulas. For closed sentences this yields a terminating truth-decision method; coordinate translation gives a corresponding decision method for elementary Euclidean geometry.

Scientific scope

Tarski gave an effective procedure converting first-order real-algebra formulas built from polynomial equations, inequalities and logical quantifiers into equivalent quantifier-free formulas. For closed sentences this yields a terminating truth-decision method; coordinate translation gives a corresponding decision method for elementary Euclidean geometry. The language ranges over real numbers with ordered-ring operations and encodable constants, not arbitrary sets/functions, unrestricted integer quantifiers or every theorem of mathematics. Parameters can remain free in a quantifier-free output; this is not a decision oracle for arbitrary uncomputably specified real coefficients. Adding an integer predicate or sine is explicitly outside the decidable language. The report does not supply a practical uniform runtime guarantee, an implementation or a resolution of real exponentiation. Fixed-size instances do not prove a variable-size universal conjecture.

Evidence

The linked original works support the scoped statement and contribution attribution. WRS has not independently replayed experiments or reconstructed a full mathematical proof. The language ranges over real numbers with ordered-ring operations and encodable constants, not arbitrary sets/functions, unrestricted integer quantifiers or every theorem of mathematics. Parameters can remain free in a quantifier-free output; this is not a decision oracle for arbitrary uncomputably specified real coefficients. Adding an integer predicate or sine is explicitly outside the decidable language. The report does not supply a practical uniform runtime guarantee, an implementation or a resolution of real exponentiation. Fixed-size instances do not prove a variable-size universal conjecture.

Contributors

Provisional WRS assessment, edition 2026-10-23.3. Independent expert calibration is pending. This grade does not certify correctness or assign ownership.

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