A Universal Framework for Forensic Decipherment and Structural Analysis of the Indus Valley Script

The Indus Valley Script (IVS), preserved on more than 5,600 inscriptions from the Mature Harappan period (c. 2600–1900 BCE), has long resisted decipherment due to the low unicity distance inherent in its inscription strings that average only 4.6 signs. This study presents the Cascade Nine, a comprehensive computational architecture designed for the structural analysis, forensic authentication, and decipherment of undeciphered writing systems. By re-framing the IVS as a Hybrid Logophonetic-Administrative System—structurally parallel to Linear A and Proto-Elamite—the framework reconciles its natural-language entropy (H=3.41 bits/token) with its ultra-short token length by proving that physical substrates and primary animal icons function as active Spatial Saturation Keyspace Operators (SAT 01) that resolve the unicity distance deficit. The pipeline was applied to the Interactive Corpus of Indus Texts (ICIT; Fuls 2022) and comparative datasets of Daimabad ceramics and Tamil Nadu megalithic graffiti (Rajan & Sivanantham 2025). The architecture identifies a stable core of high-frequency signs and recurrent syntactic templates. Under strict zero-guidance baseline testing (γ=0), the corpus exhibits unassisted semantic collapse into a South Dravidian linguistic matrix, yielding a Shannon Entropy of 3.41 bits/token, a Newman Modularity score of Q=0.68, an SVD spectral gap of λ₁/λ₂=4.7, and a 91.3% internal consistency rate across a 1,200-inscription validation population. A dedicated Benford’s Law audit on numerical stroke quantifiers (G03–G22) yields a Chi-Square fit of χ²=2.14 (p>0.92), mathematically confirming organic physical commodity accounting over artificial scribal flourishes. Furthermore, high modularity (Q=0.68) and Kullback-Leibler divergence (D_KL=0.0074) provide a robust mathematical refutation of the non-linguistic emblem thesis (Farmer et al. 2004). Stratigraphic continuity is established via Daimabad (1800–1200 BCE), which bridges the 1,000-year gap between Mature IVS and Tamil graffiti with 75.2% motif overlap across shifting ceramic media. All semantic assignments are framed as falsifiable hypotheses. Complete code, normalization scripts, and glossed lexicons are provided to support independent replication