Compressed Recurrent Feedback in Tsetlin Machines: A Reproducible Boolean-FSM Study
Authors: Ankit Kumar, Utkarsh Raj, Rishad Shafik, Sudip Roy
Organizations: Department of Computer Science and Engineering, Indian Institute of Technology Roorkee, Roorkee, India · Microsystems Research Group, Newcastle University, Newcastle upon Tyne, UK
Sequential inference on small devices requires a model to retain useful history without repeatedly processing a long input record. A Recurrent Tsetlin Machine (RTM) provides this memory by returning Boolean clause outputs from one time step as inputs to the next. Direct feedback, however, grows with the clause bank and can make the recurrent input unnecessarily wide. This paper investigates a fixed-width alternative. We combine clause activations by exclusive-OR (XOR) folding, retain the folded bits at two time scales, and threshold them back to a binary state. The resulting design reduces 480 clause activations to 96 recurrent bits. We evaluate the method on a reproducible Boolean finite-state-machine benchmark with explicit transition rules, data splits, and random seeds. Across 144 runs, the compressed model obtains 61.47±6.74% and 62.94±9.92% accuracy on the two task families. Raw clause feedback changes these means by less than one percentage point, while increasing the recurrent width tenfold and measured host execution time by 4.38× and 3.71×. Gated neural models remain more accurate, and a no-feedback control retaining only short input history achieves comparable or slightly higher accuracy. On this benchmark, folding matches raw feedback within small empirical margins at a much narrower interface; these findings also underscore the critical necessity of no-feedback recurrence controls when benchmarking sequence models.
Figures & tables
Fig. 1: Compressed RTM data flow. Clause activations are folded, retained through fast and slow exponential moving averages, and thresholded before returning at the next step. Five independently seeded members vote on the output.
Fig. 2: Boolean-FSM generator. Circuit seeds fix the hidden transition rule; dataset seeds sample initial states and observed input sequences. The label is the parity of the updated hidden state.
Family
Circuit seed
Nominal states
Distinct next
Mean out-degree
Mean bit flips
Majority baseline
Full RTM
6-bit
42
64
48
9.12
2.75
50.45%
61.38%
6-bit
43
64
48
4.50
3.25
61.74%
69.29%
6-bit
44
64
64
6.00
3.00
50.30%
53.74%
8-bit
42
256
108
6.31
4.12
55.17%
76.12%
8-bit
43
256
164
11.81
4.12
53.56%
55.42%
8-bit
44
256
192
9.69
4.00
51.51%
57.29%
TABLE I: Circuit structure, test baseline, and full-RTM accuracy (three training seeds).
Study
Factorization
Runs
RTM variants
2 families × 3 circuits × 3 seeds × 8 variants
144
Neural baselines
2 families × 3 circuits × 3 seeds × 5 models
90
State probes
first member of all RTM variant runs
144
TABLE II: Evaluation matrix.
Fig. 3: Mean test accuracy over nine matched circuit/training-seed runs. Error bars show sample SD across those runs, combining circuit and training variation; they are not confidence intervals.
Fig. 4: Paired accuracy change from the full model over nine runs; bars show 95% t intervals.
Family
Seed
Majority
MLP
RNN
GRU
LSTM
Transformer
Compressed RTM
6-bit
42
50.45
60.37
63.95
65.60
64.42
56.79
61.38
6-bit
43
61.74
73.58
71.43
77.36
76.93
61.49
69.29
6-bit
44
50.30
53.11
55.26
56.52
54.86
52.38
53.74
8-bit
42
55.17
83.68
85.91
88.32
87.81
63.51
76.12
8-bit
43
53.56
55.37
55.21
54.83
54.91
54.71
55.42
8-bit
44
51.51
60.32
63.43
65.39
65.35
54.11
57.29
TABLE III: Per-circuit test accuracy (%): mean over three training seeds. The neural and RTM columns use identical generated arrays (’Transformer’ denotes the attention-based baseline).
Variant
6-bit accuracy
8-bit accuracy
Full compressed
61.47 ± 6.74%
62.94 ± 9.92%
No clause feedback
61.91 ± 6.49%
63.83 ± 9.89%
Single member
59.70 ± 6.63%
60.65 ± 8.79%
32-bit fold
61.47 ± 6.51%
63.31 ± 9.96%
No thermometer
61.25 ± 6.79%
62.26 ± 9.46%
Single timescale
62.18 ± 6.26%
63.78 ± 10.00%
TABLE IV: Ablations: mean accuracy ± SD over nine runs.
Measure
6-bit
8-bit
Compressed accuracy
61.47%
62.94%
Uncompressed accuracy
62.19%
63.52%
Paired Δ (95% CI)
+0.72 [ −0.22,1.65 ]
+0.58 [ −0.48,1.63 ]
Feedback-state bits
96→960
96→960
Total input dimension
182→1046
182→1046
Mean run time (min)
16.6→72.7
19.7→73.2
TABLE V: Compressed versus raw feedback; Δ is raw minus compressed accuracy.
Family
Feedback
Top-1
U-Top-1
Top-5
U-Top-5
6-bit
Compressed
1.08 ± 0.85%
1.92%
6.35 ± 3.81%
9.62%
6-bit
Uncompressed
15.40 ± 9.71%
1.92%
38.30 ± 18.66%
9.62%
8-bit
Compressed
0.086 ± 0.057%
0.73%
0.51 ± 0.17%
3.63%
8-bit
Uncompressed
8.01 ± 7.34%
0.73%
25.86 ± 16.63%
3.63%
TABLE VI: Probe accuracy (mean ± SD) and matched uniform references (mean), nine runs.
Robotics and Perception Group, University of Zurich · Shenzhen International Center for Industrial and Applied Mathematics, Shenzhen Research Institute of Big Data · Tengen Intelligence Institute, CRRC Zhuzhou Institute