math.NT — Number Theory
A lattice-theoretic approach to the abc conjecture: Weighted arithmetic derivatives, a master inequality, and the structure of the residual family
We develop a self-contained lattice-theoretic framework for the abc conjecture. For coprime positive integers with , the framework rests on a weighted arithmetic derivative whose additivity equation is solvable modulo the modulus , and on a Wronskian identity , where and is an explicit linear form. A divisibility lemma and an elementary upper bound yield the master inequality , in which the defect factor is the shortest non-kernel weight of an explicit solution lattice of determinant . Writing , geometry-of-numbers input (Hermite's bound and an orthogonal covering-radius sandwich; an earlier ``min--max barrier'' is falsified in Theorem 4.5) yields, conditionally on an explicit gap hypothesis isolated in Section 7, the bound , whence , i.e.\ . On the subclass the method closes unconditionally (Zsigmondy for ; cyclotomic/LTE control of valuations for ). The residual family is localized by a power--congruence bridge: forces into a single residue class modulo (, the Wieferich depth), of convergent total density; the unique unclosed layer reduces to growth-difference Pillai-type equations. We also prove a structural ceiling: the main term of is at most and attains on the family , so the full abc conjecture () is structurally unreachable inside this framework. A final section determines the reach and limits of the method elementarily: almost all have every coprime decomposition with (density theorem, by one-variable counting, exceptional set ), while any argument within the method class cannot prove for any (obstacle theorem), and the only remaining channel is equivalent to a sparse growth-difference Pillai core. All statements are proved in full or are explicitly labelled as working hypotheses; numerical cross-checks from two independent implementations are included, and no claim of a proof of the abc conjecture is made.