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MathlibNt.SieveTheory.LinearSieve.FiniteWeights

Finite Moebius, Selberg, and lower Rosser weights #

Finite lower and upper sieve inequalities, lower Rosser coefficients, and Euler-normalized lower density recursions.

0. Finite lower-bound sieve interface #

A sequence of coefficients is lower Möbius when its divisor sums lie below the coprimality indicator. This is the exact finite dual of Mathlib's BoundingSieve.IsUpperMoebius.

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    A lower Möbius sequence gives a lower bound for the sifted sum before any asymptotic estimate is introduced.

    Explicit-error lower sieve inequality. Unlike the historical pointwise interfaces, the loss is the concrete finite quantity errSum muMinus.

    0.1. Finite upper Selberg weights #

    A coefficient sequence has upper-sieve level support when it vanishes on divisors of P outside the strict natural-number level D.

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      The upper Möbius condition restricted to divisors of a fixed finite prime product. This is the exact amount of positivity used by a finite sieve.

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        A finite upper-Möbius coefficient bounds the sifted sum from above.

        The exact finite upper-sieve remainder sum at level D.

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          Finite upper sieve inequality with no Selberg representation: an upper Möbius certificate on divisors and level support are sufficient.

          A finite Selberg upper weight records the underlying lambda, its normalization, and the level support of the resulting lambdaSquared coefficient.

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            The explicit upper coefficient generated by a finite Selberg weight.

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              Finite upper Selberg inequality with the main sum and the exact level-restricted remainder sum kept separate.

              0.2. Finite lower Rosser weights #

              The lower Möbius condition needed by a sieve with the fixed finite product P. Requiring it for all natural numbers, as IsLowerMoebius does, is unnecessarily strong for a finite sieve.

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                The error sum at a natural level. It deliberately contains only d < D; this is the finite error term occurring in the lower fundamental lemma.

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                  A coefficient sequence has level support if it vanishes outside the divisors below the level.

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                    Finite lower sieve inequality with its error sum explicitly restricted to the level.

                    The standard lower Rosser test on a finite set of distinct primes. For a prime p in an even position of the decreasing list, the filter is precisely the prefix p₁,…,p₂l; thus its test is p₁⋯p₂l₋₁ * p₂l^3 < D.

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                      The explicit finite lower Rosser/Jurkat coefficient. The d < D clause is part of the finite-level convention; the source admissibility test is LowerRosserAdmissible.

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                        theorem MathlibNt.SieveTheory.LinearSieve.lowerRosser_insert_min_active_iff_cube_lt {D q : } {s : Finset } (hqs : qs) (hqprime : Nat.Prime q) (hqmin : ps, q p) (hodd : ¬Even s.card) (hs : s.prod id < D LowerRosserAdmissibleSet D s) :

                        For an active odd set, adjoining a new least prime remains active exactly until the cubic lower-Rosser cutoff q ^ 3 * ∏ s < D is crossed.

                        theorem MathlibNt.SieveTheory.LinearSieve.lowerRosserBoundarySet_iff_cube_le {D q : } {s : Finset } (hqs : qs) (hqprime : Nat.Prime q) (hqmin : ps, q p) :

                        The abstract odd lower-Rosser boundary is exactly the cubic shell D ≤ q ^ 3 * ∏ s once q is the new least prime.

                        theorem MathlibNt.SieveTheory.LinearSieve.lowerRosserSetWeight_insert_min_pair (nu : ) {D q : } {s : Finset } (hqs : qs) (hqprime : Nat.Prime q) (hqmin : ps, q p) (hodd : ¬Even s.card) (hs : s.prod id < D LowerRosserAdmissibleSet D s) :

                        Exact lower-Rosser one-prime pairing on an active odd tail. The ordinary Euler factor survives away from the cubic shell, while crossing the shell contributes one negative boundary term.

                        The finite lower Rosser density sum over subsets of a prescribed prime set. This is the lower-sieve counterpart of upperRosserSetDensitySum.

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                          theorem MathlibNt.SieveTheory.LinearSieve.lowerRosserSetWeight_insert_min_pair_all (nu : ) {D q : } {s : Finset } (hqs : qs) (hqprime : Nat.Prime q) (hqD : q < D) (hqmin : ps, q p) :

                          Exact one-prime pairing, including inactive and even tails.

                          theorem MathlibNt.SieveTheory.LinearSieve.lowerRosserSetDensitySum_insert_min (nu : ) {D q : } {P : Finset } (hqP : qP) (hqprime : Nat.Prime q) (hqD : q < D) (hqmin : pP, q p) :
                          lowerRosserSetDensitySum nu D (insert q P) = (1 - nu q) * lowerRosserSetDensitySum nu D P - nu q * sP.powerset with (LowerRosserBoundarySet D q) s, ps, nu p

                          Adjoining a new least prime gives the exact Euler factor, minus precisely its odd cubic-boundary contribution.

                          theorem MathlibNt.SieveTheory.LinearSieve.lowerRosserSetDensityRatio_insert_min (nu : ) {D q : } {P : Finset } (hq : qP) (hqprime : Nat.Prime q) (hqD : q < D) (hqmin : pP, q p) (hqFactor : 1 - nu q 0) (hPFactor : pP, (1 - nu p) 0) :
                          lowerRosserSetDensitySum nu D (insert q P) / pinsert q P, (1 - nu p) = lowerRosserSetDensitySum nu D P / pP, (1 - nu p) - nu q / (1 - nu q) * ((∑ sP.powerset with (LowerRosserBoundarySet D q) s, ps, nu p) / pP, (1 - nu p))

                          Euler-product-normalized form of the one-prime lower recurrence. This is pure finite algebra; the nonzero assumptions are kept explicit and no limiting or contraction statement is used.

                          Finite Euler-normalized lower recursion #

                          This deliberately stays at one finite recursion step. In particular it does not package an all-depth tail or introduce a continuous majorant.

                          The lower Rosser density on the relative Euler-product scale.

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                            The finite odd-boundary correction on the same relative Euler-product scale as lowerRosserSetRelativeDensity.

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                              theorem MathlibNt.SieveTheory.LinearSieve.lowerRosserSetRelativeDensity_insert_min (nu : ) {D q : } {P : Finset } (hqP : qP) (hqprime : Nat.Prime q) (hqD : q < D) (hqmin : pP, q p) (hqFactor : 1 - nu q 0) (hPFactor : pP, (1 - nu p) 0) :

                              Exact normalized successor identity when a new least prime is adjoined. The lower recursion subtracts, rather than adds, its odd-boundary mass.

                              theorem MathlibNt.SieveTheory.LinearSieve.lowerRosserBoundaryRelativeDensity_nonneg (nu : ) {D q : } {P : Finset } (hnu : pP, 0 nu p) (hnuOne : pP, nu p < 1) :

                              A finite lower boundary has nonnegative relative density under the local sieve bounds 0 ≤ nu p < 1.

                              theorem MathlibNt.SieveTheory.LinearSieve.lowerRosserSetRelativeDensity_insert_min_le (nu : ) {D q : } {P : Finset } (hqP : qP) (hqprime : Nat.Prime q) (hqD : q < D) (hqmin : pP, q p) (hnuq : 0 nu q) (hnuqOne : nu q < 1) (hnu : pP, 0 nu p) (hnuOne : pP, nu p < 1) :

                              Monotone normalized successor interface: adjoining a least prime can only decrease the relative lower density when 0 ≤ nu < 1.

                              Terminal base for the finite normalized lower recursion.

                              theorem MathlibNt.SieveTheory.LinearSieve.lowerRosserSetDensitySum_insert_min_cube (nu : ) {D q : } {P : Finset } (hqP : qP) (hqprime : Nat.Prime q) (hqD : q < D) (hqmin : pP, q p) :
                              lowerRosserSetDensitySum nu D (insert q P) = (1 - nu q) * lowerRosserSetDensitySum nu D P - nu q * sP.powerset with ¬Even s.card s.prod id < D LowerRosserAdmissibleSet D s D s.prod id * q ^ 3, ps, nu p

                              Cubic-shell form of lowerRosserSetDensitySum_insert_min.

                              The cubic-boundary mass lost when the new least prime q is inserted.

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                                The total (unnormalized) boundary loss in a finite sequence of least-prime insertions. Earlier losses are multiplied by all Euler factors inserted later.

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                                  theorem MathlibNt.SieveTheory.LinearSieve.lowerRosserSetDensitySum_foldr_insert (nu : ) (D : ) (P : Finset ) (qs : List ) (hprime : qqs, Nat.Prime q) (hD : qqs, q < D) (hordered : List.Pairwise (fun (x1 x2 : ) => x1 < x2) qs) (hdisjoint : qqs, qP) (hbase : qqs, pP, q p) :

                                  Exact finite iteration of the lower Rosser density recurrence.

                                  The list is ordered increasingly, so foldr insert P inserts its largest prime first and its smallest prime last. The formula uses no division by Euler factors; consequently it needs no positivity or nonvanishing hypothesis on 1 - nu q.

                                  The BoundingSieve.mainSum of the explicit lower Rosser coefficient is exactly its finite subset density sum. This is the first finite transport edge from Suzuki's Rosser--Iwaniec coefficient to the density recursion.

                                  A finite Rosser certificate is the combinatorial toggle-min conclusion: even admissible subsets inject into odd admissible subsets. Its consequence is exactly the lower divisor-sum inequality needed by BoundingSieve.

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                                    The explicit lower Rosser weight is an unconditional finite lower-Möbius certificate for a squarefree prime product whose prime factors lie below the level.

                                    A certified lower Rosser weight supplies the finite divisor-sum lower bound, while retaining the explicit source formula above.