Organizations: University of Sydney Sydney, Australia · Nanjing University of Science and Technology Nanjing, China · Edith Cowan University Perth, Australia · National University of Singapore Singapore
Large language models are typically evaluated in terms of the correctness of their output. However, output correctness alone does not confirm whether the latent knowledge supporting an answer has stable internal representations. We therefore propose latent state stability (LSS) and knowledge topology stability (KTS) to investigate the stability of individual knowledge states and their relational structure, respectively. Specifically, we first separately average the model's internal representations of the same knowledge under each elicitation condition. Using the mean representation under the baseline condition as a reference, we remove shared shifts to obtain corrected representations. We then formulate LSS as the distance between each corrected representation and its reference representation, normalized against the typical distance between knowledge items of the same type. We formulate KTS as the cross-condition consistency of the ordered pairwise representation distances among knowledge items of the same type. Next, we construct EpiStableBench, which comprises 4,411 items spanning factual knowledge and mathematical reasoning, with 76,766 controlled queries. Across 16 LLMs from four families, representation stability varies substantially even among items answered correctly under the base condition. Within models, higher stability generally corresponds to higher accuracy under held-out elicitation conditions; across models, stability does not consistently increase with model size or overall accuracy. Meanwhile, we present LatentDPO to learn a knowledge-editing policy that accounts for the stability of latent knowledge. Experimental results show that integrating LatentDPO with multiple existing editing methods consistently improves editing success and generalization across different expressions.
Figures & tables
Figure 1: Motivation For The Correctness–Stability Hypothesis. (a) Human intuition suggests that well-established knowledge should consistently yield correct answers. (b) In LLMs, an initially correct answer may either persist or fail in subsequent elicitation conditions. (c) These observations motivate the hypothesis that model outputs may vary with representational stability.
Figure 2: Overview of EpiStableBench. (a) Canonical questions and four controlled-query types varying paraphrase, format, context, and language for factual knowledge ( orange ) and mathematical reasoning ( blue ). (b) Distribution of 4,411 knowledge items across domains and categories.
Table 1: Model-Family and Scaling Comparison. ACC, LSS, and KTS are reported across open-weight LLM families and parameter scales for factual knowledge, mathematical reasoning, and their average. The best and second-best results are shown in bold and underlined . More results, please see the appendix.
Figure 3: Behavioral Errors Accompanied By Latent Shifts. Items answered correctly under baseline elicitation condition produce competing answers under changed elicitation conditions, accompanied by representational shifts toward facts associated with those answers. More results please see the appendix.
Figure 4: Stability and Subsequent Correctness. Among targets answered correctly under the base condition, high-LSS targets and high-KTS groups show higher ACC under held-out elicitation conditions than their low-stability counterparts.
Figure 5: Semantic Sensitivity of LSS and KTS. Hard negatives induce larger metric changes than target-preserving perturbations across all three models.
Figure 6: Separating Shared Shifts from Item-Specific Drift. (Left) Decomposition of normalized squared drift into the portion removed by alignment and the remaining residual. (Right) Gains in answer-change prediction across alignment variants, measured in AUROC points.
Setting
LSS
KTS
Model
Item
Model
Relation
No Norm. / Centering
0.23
0.65
0.99
0.93
Global Norm. / Structure
0.84
0.64
0.77
0.15
Table 2: Relation-Aware Processing. Spearman correlations between ablated and full-method scores at the indicated aggregation levels. Labels before and after the slash denote LSS and KTS variants, respectively.
Setting
LSS
KTS
Model
Item
Model
Relation
Depth 40%–60%
0.14
0.42
-0.10
0.59
Depth 60%–80%
0.68
0.77
0.53
0.85
Depth 80%–100%
0.96
1.00
0.99
1.00
Final Layer Only
0.60
0.84
0.98
0.95
Raw States, Final 25%
0.47
0.82
0.89
0.80
Table 3: Representation and Layer Selection. Spearman correlations with the full method, which aggregates J-Lens representations over the final 25% of layers. Depth is normalized from input to output.
Setting
LSS
KTS
Model
Item
Model
Relation
Leave-one-probe-out
Drop Paraphrase
0.98
0.97
0.99
0.97
Drop Format
0.96
0.95
0.97
0.96
Drop Context
0.95
0.95
0.92
0.91
Drop Multilingual
0.95
0.95
0.93
0.90
Table 4: Probe and Reference Sensitivity. Spearman correlations with the full method after omitting an elicitation family or changing the reference condition.
Figure 7: Geometric Patterns of Internal Knowledge Stability. Representative high- and low-LSS items and high- and low-KTS relations are compared across the base and controlled elicitation conditions.
Figure 8: Layer-Specific Activation Patching. Target-answer recovery from same-item canonical states versus different-item controls within the same relation.
Figure 9: Family-Specific Sensitivity to Elicitation. Condition-wise changes in ACC, LSS, and KTS relative to the base condition across four model families.
Method
GPT2-XL
LLaMA 2-7B
Accuracy ↑
Generality ↑
Specificity ↑
Accuracy ↑
Generality ↑
Specificity ↑
ROME
99.40
73.67
80.61
99.90
67.37
93.87
ROME + Ours
99.65 (+0.25)
80.48 (+6.81)
80.27 (-0.34)
99.90 (+0.00)
75.75 (+8.38)
93.33 (-0.54)
MEMIT
72.37
38.89
87.57
76.08
54.23
74.40
MEMIT + Ours
87.14 (+14.77)
54.98 (+16.09)
86.94 (-0.63)
90.79 (+14.71)
69.17 (+14.94)
73.52 (-0.88)
SAKE
94.59
83.96
84.20
96.70
80.73
84.67
Table 5: Application to Knowledge Editing. Accuracy, Generality, and Specificity (%) under identical edit sets and evaluation protocols. Parentheses report percentage-point changes relative to the baseline.
Appendix figures & tables9 assets
Supplementary material from the paper’s appendix.
Appendix
Symbol
Definition
m,ℓ,i,q
Model, layer, knowledge item, and query, respectively.
I,IF,IM
All knowledge items and the factual-knowledge and mathematical-reasoning subsets, respectively.
ki=(xi,ri,yi)
Knowledge item i , where xi is the queried content, ri is its benchmark-defined comparison group, and yi is the target answer.
τi∈{F,M}
Track containing item i , where F and M denote the factual-knowledge and mathematical-reasoning tracks, respectively.
a,T,Ti
Reference elicitation condition a , elicitation-condition families T , and the conditions Ti⊆T available for item i .
Qi,t
Set of target-preserving queries for item i under elicitation condition t .
Appendix
Table 6: Core notation for Latent State Stability (LSS) and Knowledge Topology Stability (KTS).
Predictor
Qwen2.5-3B
Qwen2.5-7B
Strong Output Baseline
0.5993
0.7150
+ Within-relation CKA
0.6033
0.7166
+ All Standard Features
0.6030
0.7137
+ LSS
0.6102
0.7169
+ KTS
0.6149
0.7262
+ LSS/KTS
0.6154
0.7333
Appendix
Table 7: Comparison With Standard Representation Measures. All representation features augment the same strong output baseline. Values report failure-prediction AUROC.
Ablation
LSS Rank Correlation
Calibration Corpus
0.964 – 0.990
J-Lens Transport Rank
0.903 – 0.991
Raw/PCA Representations
0.373 – 0.780
Question-level Pooling
0.161 – 0.561
Appendix
Table 8: Sensitivity to J-Lens and Representation Choices. LSS rank correlations under changes to the calibration corpus, transport rank, representation space, and token extraction position.
Figure 10: KTS Reliability Across Relation Sizes. Reliability increases with the number of shared items, with both relation-level and condition-pair estimates exceeding the 90% target at 200 items.
Metric
Setting Change
Rank ρ
Max. Shift
KTS
Alternative Tie Conventions
1.000
0
Shared-item Threshold: 100→10
0.985
2
Item-weighted Relations
0.974
2
LSS
Additive Constant: 0 – 10−3
1.000
0
Item-weighted Relations
0.988
2
Appendix
Table 9: Sensitivity to Numerical and Aggregation Choices. Spearman correlations and maximum rank shifts are measured against the default settings across 16 models in the audited factual cohort. The LSS constant row summarizes all seven tested settings; other rows concern the full method.
Figure 11: More Qualitative Analysis of LSS.
Figure 12: More Qualitative Analysis of KTS.
Table 10: Extended Model Rankings. ACC, LSS, and KTS are reported for 43 additional model configurations across 11 model families. The best and second-best results in each column are shown in bold and underlined, respectively.
Backbone
Editor
αb,e
τb,e
GPT2-XL
ROME
0.75
5.25
MEMIT
0.50
5.50
SAKE
1.00
6.75
LLaMA 2-7B
ROME
0.75
5.25
MEMIT
0.25
5.55
SAKE
1.00
6.75
Appendix
Table 11: Frozen Gated-Correction Configurations. Correction strength αb,e and prompt-gate threshold τb,e used to construct action 1 .