Darwin-9B-Opus is a 9B dense parameter reasoning model created using Darwin V5. Both parent models share the identical Qwen3.5-9B architecture — the Mother is a LoRA SFT on the same base, not a different architecture.
LoRA SFT with text-only Claude 4.6 Opus reasoning chains
How Darwin V5 Works
Darwin V5 does not use mergekit or any external merge library. It implements DARE-TIES merge directly via PyTorch tensor operations, with MRI-guided per-layer ratios. The algorithm is inspired by the DARE-TIES method but re-implemented from scratch to support per-tensor diagnostic-guided ratios.
Merge Implementation (actual code logic)
python
1# For each tensor pair (A, B) across all safetensor shards:2ta = model_a[key]# Father tensor3tb = model_b[key]# Mother tensor45# 1. MRI diagnoses both tensors6diag_a = LayerMRI.diagnose_tensor(ta)# {norm, entropy, std}7diag_b = LayerMRI.diagnose_tensor(tb)# {norm, entropy, std}89# 2. Quality score comparison determines ratio_b10score_a = diag_a["entropy"]*0.5+ diag_a["std"]*0.3+min(diag_a["norm"],100)*0.00211score_b = diag_b["entropy"]*0.5+ diag_b["std"]*0.3+min(diag_b["norm"],100)*0.00212mri_ratio = score_b /(score_a + score_b)# Higher = Mother is better1314# 3. Final ratio = MRI 70% + evolutionary genome 30%15final_ratio = mri_ratio *0.7+ genome_type_ratio *0.31617# 4. DARE-TIES merge with per-tensor ratio18mask = torch.rand_like(tb)< density_b
19delta =(tb - ta)* mask
20merged =(ta + delta * final_ratio).bfloat16()
Pipeline
Phase 0: Model MRI
For every tensor in both parents, measure:
- L2 norm (layer energy)
- Shannon entropy (weight distribution uniformity)
- Standard deviation (activation spread)
Compare A vs B quality scores -> per-tensor ratio prescription
Phase 1: Evolutionary Search (200 steps, heuristic proxy)
Population of 20 genomes (ratio, attn, ffn, embed, density_a, density_b)
Fitness: heuristic score based on genome balance + differentiation
Selection -> SLERP crossover -> Gaussian mutation
Phase 2: Real Merge + Benchmark (10 steps)
Top genomes from Phase 1 undergo actual tensor merge
Each merge: MRI prescription (70%) + genome ratio (30%)
Fitness: real benchmark score (ARC-Challenge)
Best model selected and auto-uploaded
Phase 3: Health Check
Layer-by-layer importance comparison: child vs both parents
Detect interference (child >> parents) or function loss (parents >> child)
What Makes This Different from Standard Merging
Capability
Standard DARE-TIES
Darwin V5
Implementation
mergekit library call
Direct PyTorch tensor operations
Ratio selection
Uniform ratio across all tensors
Per-tensor ratio from MRI diagnosis
Pre-merge analysis
None
Tensor-level norm/entropy/std profiling
Ratio determination
Human-set or grid search
MRI 70% + evolutionary genome 30%
Post-merge validation
Benchmark score only
Layer-by-layer child vs parents comparison
Transplant support
No
ratio < 0.05 -> use A entirely, ratio > 0.95 -> use B entirely