Document Deep CFR selectivity findings

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# Deep CFR Selectivity Investigation
Last updated: 2026-05-09
## Current conclusion
The current Deep CFR baseline is not mainly blocked by model size or LCFR
time-weighting. The strongest signal so far is a selectivity failure: the model
does not reliably learn to distinguish good first opens from bad first opens.
The `outcome_sampling_epsilon=0.05` setting produced a short-run improvement
around 200 iterations, but the improvement did not hold through 500 iterations.
Weighting ablations did not recover the 200-iteration peak, so further LCFR
alpha tuning is lower priority than directly inspecting or changing the
first-open advantage target.
## Baseline symptoms
The 512x3 dense-eval baseline showed improving training losses, but the main
game-quality metrics against `safe_heuristic_strict` did not improve enough to
indicate a useful policy.
Observed pattern:
- Advantage loss can move in the expected direction while eval quality remains
poor.
- Bad first-open behavior stays high.
- Open quality, measured by score per opened color, stays negative.
- Current-policy evaluation did not rescue the result, so the issue is not only
average-policy lag.
## Closed hypotheses
### More outcome sampling helps, but only up to a point
Short 200-iteration ablations with `outcome_unsampled_regret=zero`:
| setting | safe strict score diff | win rate | bad open rate | score/opened color |
| --- | ---: | ---: | ---: | ---: |
| `epsilon=0.20` | -57.87 | 0.07 | 0.901 | -8.40 |
| `epsilon=0.10` | -58.66 | 0.05 | 0.913 | -8.63 |
| `epsilon=0.05` | -40.01 | 0.12 | 0.893 | -6.25 |
| `epsilon=0.02` | -53.55 | - | - | - |
Conclusion: `epsilon=0.05` was the best short-run candidate. Lowering to
`0.02` was worse, and larger values were also worse.
### Negative unsampled regret was not sufficient
The `epsilon=0.05` plus `outcome_unsampled_regret=negative_node_value` variant
ended around safe strict score diff `-44.53` at 200 iterations, worse than
`epsilon=0.05` with `zero`.
Conclusion: the negative target suppresses opening, but it does not selectively
preserve good opens.
### The 200-iteration epsilon=0.05 peak did not hold
Confirmation run:
- Run: `runs/2026-05-09_010747_confirm-eps-005-zero-512x3-det-500`
- W&B group: `eps005-confirmation-512x3-v1`
- Config delta:
- `run.deterministic=true`
- `run.max_iterations=500`
- `traversal.outcome_sampling_epsilon=0.05`
- `traversal.outcome_unsampled_regret=zero`
Safe heuristic strict metrics:
| iteration | win rate | score diff | bad open rate | score/opened color |
| ---: | ---: | ---: | ---: | ---: |
| 200 | 0.12 | -40.01 | 0.893 | -6.25 |
| 250 | 0.08 | -46.91 | 0.900 | -7.29 |
| 300 | 0.08 | -45.93 | 0.895 | -6.30 |
| 350 | 0.07 | -54.02 | 0.899 | -7.83 |
| 400 | 0.04 | -49.64 | 0.912 | -7.83 |
| 450 | 0.06 | -49.31 | 0.917 | -6.71 |
| 500 | 0.06 | -61.24 | 0.903 | -8.30 |
Conclusion: `epsilon=0.05` creates a real short-run peak, but the behavior is
not stable through 500 iterations.
### LCFR time-weighting is not the sole cause of the degradation
Weighting ablation group:
- W&B group: `eps005-weighting-ablation-512x3-v1`
- Common config:
- `run.deterministic=true`
- `run.max_iterations=300`
- `traversal.outcome_sampling_epsilon=0.05`
- `traversal.outcome_unsampled_regret=zero`
Compared runs:
| run | iter 200 diff | iter 250 diff | iter 300 diff | iter 300 win | iter 300 bad open |
| --- | ---: | ---: | ---: | ---: | ---: |
| LCFR alpha=1.0 confirmation | -40.01 | -46.91 | -45.93 | 0.08 | 0.895 |
| `training_weighting.mode=none` | -50.98 | -48.46 | -56.27 | 0.04 | 0.912 |
| `training_weighting.lcfr_alpha=0.5` | -66.81 | -58.97 | -50.77 | 0.10 | 0.891 |
Open-quality comparison:
| run | iter 200 score/opened color | iter 300 score/opened color |
| --- | ---: | ---: |
| LCFR alpha=1.0 confirmation | -6.25 | -6.30 |
| `training_weighting.mode=none` | -7.71 | -7.70 |
| `training_weighting.lcfr_alpha=0.5` | -9.94 | -7.85 |
Conclusion: neither removing time-weighting nor softening LCFR to `alpha=0.5`
beat the original `alpha=1.0` confirmation by the primary score-diff metric at
300 iterations. LCFR may affect stability, but it is not the main lever.
## First-open diagnostic
Diagnostic output:
- `runs/tmp/first_open_advantage_confirm_eps005_200_vs_500.jsonl`
Observed values:
| checkpoint | bad selection | good selection | bad advantage | good advantage | sampled turns |
| --- | ---: | ---: | ---: | ---: | ---: |
| iter 200 | 0.0625 | 0.0582 | -12.82 | -16.60 | 8560 |
| iter 500 | 0.0067 | 0.0067 | -35.42 | -44.32 | 40942 |
Interpretation: by 500 iterations the model strongly suppresses opening
overall. It suppresses good opens along with bad opens, which is the core
selectivity failure.
## Open questions
1. Does the traversal target itself provide separable labels for good first
opens versus bad first opens?
2. Is the model receiving too sparse or too noisy a signal at the first-open
decision point?
3. Would target shaping around first-open decisions improve score/opened color
without increasing bad-open rate?
4. Is evaluation showing a policy-selection problem, or is the advantage model
already misranking good and bad opens before strategy extraction?
## Recommended next experiments
### 1. Deeper first-open target audit
Before another long training run, inspect sampled first-open decision records
more directly:
- Group candidate first-open actions into good-open and bad-open buckets.
- Compare target values before model prediction, not only final learned
advantages.
- Report distributions, not just means.
- Check whether the target ranks good opens above bad opens in the same
information-state context family.
Success criterion: the target distribution should show a usable separation
between good and bad opens. If it does not, the training target is the blocker.
### 2. Short open-selectivity ablation
Run a 200-300 iteration ablation only after the target audit identifies a
specific change. Candidate changes include:
- first-open target shaping,
- modified unsampled-open penalty,
- outcome sampling focused on open-relevant branches,
- or strategy/eval selection that separates current and average policy at the
open decision.
Primary metrics:
- `eval/safe_heuristic_strict/avg_score_diff0`
- `eval/safe_heuristic_strict/win_rate0`
- `eval/safe_heuristic_strict/bad_open_rate`
- `eval/safe_heuristic_strict/score_per_opened_color`
Do not promote to 500+ iterations unless bad-open rate and score/opened color
both improve without degrading score diff.
## Operational notes
- Keep one GPU training run active at a time.
- Use `tmux` plus `.compute.lock` for training.
- Mirror real experiments to W&B.
- Use one W&B group per hypothesis family.
- Do not start a long 2000-iteration run until a short diagnostic run shows
stable selectivity improvement.