Indonesian Artist Case: Pemodelan Semiotika Matematis Linimasa Kasus Hukum Ruben Onsu vs Sarwendah - Mediasi Gagal, Hak Asuh Anak, dan Saling Gugat Wanprestasi Akta 39

This study presents an Indonesian Artist Case study through Pemodelan Semiotika Matematis, a mathematical-semiotic timeline model of the Ruben Onsu vs Sarwendah legal case, using the quadratic function f(x) = -x² + 45x + 1/4. The 45-week driving factor represents the total case cycle. The axis of symmetry at x = 22.5 weeks, 3 June 2026, marks the saturation point of case intensity with a peak value of 506.5 hours. The model is applied to three phases: pre-mediation, mediation, and post-mediation, including the child custody claim, the failed mediation, the mutual breach of contract claim on Deed 39 (Case No. 1198/Pdt.G/2026/PN JKT.SEL), and the first hearing on 13 October 2026. A working-day simulation from 30 June to 13 August yields 31 effective working days and 713 net hours, close to the function total of 709 hours, supporting the projection of mediation failure before the formal ruling.