State-of-the-art temporal-link-prediction (TLP) models are, in essence, multi-channel information aggregators: they combine an interaction-history channel, a time-encoding channel, and a structure channel. The first two have been refined relentlessly; the structure channel remains a crude afterthought -- DyGFormer encodes it as a 1--2-bit neighbour-cooccurrence count. We begin with a measurement: on sparse temporal graphs the classical 1-hop common-neighbour signal is near-random (discriminative AUC ≈0.50), because two nodes almost never share a direct neighbour; the genuinely discriminative signal lies one hop deeper -- the 2-hop cohesive bridge, whose discAUC reaches 0.73--0.98, on both bipartite and non-bipartite graphs. Motivated by this, we propose HAWKEYE, a cohesion-aware structural channel that incrementally maintains the classical k-family of cohesiveness indicators (degree → k-core → k-truss) and forms 2-hop cohesive-bridge features. HAWKEYE is a drop-in replacement for a temporal-graph model's native structure channel, with no change to the backbone. Swapping HAWKEYE into DyGFormer improves test AP/MRR over the cooccurrence channel by +0.6 to +10.8 points across six multi-seed-validated datasets (uci, enron, USLegis, CanParl, reddit, mooc). On the bipartite recommendation benchmark tgbl-subreddit, a 3-seed single-pass struct-only ablation shows HAWKEYE nearly doubling the baseline test MRR (0.103±0.003 → 0.204±0.005, +10.1 points across all three seeds); the streaming pipeline scales to the 67M-edge tgbl-flight in five minutes per pass. We further characterise when it helps: the gain tracks a graph's training-free 2-hop discAUC and vanishes on degenerate or saturated graphs -- a predictable boundary. All code, data, and figure-generation scripts are released.
Figures & tables
Figure 1. Running example (used throughout the paper). In a corporate email network, Alice ( u ) and Bob ( v ) have never emailed each other, so the 1-hop common-neighbour count is CN=0 ; a cooccurrence-based structure channel sees no signal. Yet two 2-hop paths connect them: Alice–Carol–Dan and Alice–Eve–Grace, where Dan (core 5 ) and Grace (core 4 ) are Bob’s direct neighbours and Carol, Eve are the length-two intermediaries from Alice. Hawkeye reads exactly these bridges and correctly rates Alice–Bob as a likely next-email pair. Section 3 shows this configuration is the typical informative pair on sparse temporal graphs; Section 4 explains how the cache and the slot encoder make Alice’s, Bob’s, and the intermediaries’ coreness available at query time; and § 5.6 returns to this example in the case study.
Table 1. Discriminability AUC of 1-hop vs. 2-hop structural signals (discAUC =0.50 is random). 1-hop CN is random on sparse graphs; the 2-hop cohesive bridge is strongly discriminative.
Figure 2. Hawkeye per-batch timing, threaded with the Alice/Bob running example. Gray boxes are CPU work (Cohesion Cache + slot-feature extraction), blue boxes are GPU work (Cohesion Slot Encoder + unchanged DyGFormer). Orange badges P1–P8 mirror the steps of Algorithm 2 ; the orange feedback arrow is the “predict-then-advance” contract that commits the batch’s edges after they have been scored.
component
time
space
adjacency maintenance
O(1) /edge
O(N+M)
degree update
O(1) /edge
O(N)
core-number update
O(∣S∣) /edge
O(N)
trussness update (opt.)
up to O(m1.5)
O(M)
2-hop bridge extraction
O(dudmax) /query
O(dmax) transient
Cohesion Slot Encoder
O(dfeat⋅ch) /slot
∼103 params
Table 2. Per-edge / per-query overhead of Hawkeye over the backbone. ∣S∣ is the (small) core-affected set; du,dmax are degrees.
dataset
source
nodes
edges
dˉ
type
tgbl-wiki
TGB
9,227
157,474
4.0
bipartite
tgbl-uci
TGB
1,899
59,835
14.6
non-bipartite
tgbl-enron
TGB
184
125,235
24.1
non-bipartite
tgbl-subreddit
TGB
10,984
672,447
14.3
bipartite
tgbl-lastfm
TGB
1,980
1.29 M
156.6
bipartite
tgbl-review
TGB
352,637
4.87 M
26.8
bipartite
Table 3. Dataset statistics used in this paper. Counts are direct from the released edge files. dˉ is the average static degree : distinct neighbours per node over the full stream, dˉ=2∣Estatic∣/∣V∣ — the quantity that governs the sparsity mechanism of § 3 (the 1-hop CN degenerates when dˉ≪∣V∣ ). TGB datasets above the rule are used for the main DyGFormer + Hawkeye results; the lower TGB block lists the large-graph datasets used in the scalability experiments (§ 5.4 ); DGB datasets follow the DyGLib ( 35 ) release.
configuration
uci
enron
CanParl
USLegis
mooc
reddit
DyGFormer (none)
0.838±.001
0.771±.007
0.680±.045
0.715±.005
0.797±.001
0.966±.000
DyGFormer (cooccur)
0.956±.000
0.917±.000
0.708±.008
0.719±.001
0.857±.001
0.975±.014
DyGFormer ( + Hawkeye )
0.942±.004
0.924±.001
0.816±.001
0.768±.004
0.915±.007
0.974±.014
DyGFormer ( ⊕ Hawkeye )
0.962±.001
0.930±.001
0.821±.002
0.770±.003
0.917±.003
0.966±.000
Table 4. Structure-channel swap-in on DyGFormer (DGB protocol, test AP). All entries 3-seed mean ± std under the current code. Bold : best per dataset. tgbl-wiki (TGB MRR) is reported separately in Table 6 .
dataset
edges
baseline
with Hawkeye
gain
tgbl-subreddit
672K
0.103±.003
0.204±.005
+10.1★
tgbl-review
4.87 M
0.283±.002
0.2751
−0.8
tgbl-lastfm
1.29 M
0.008
0.007
≈0
Table 5. Large-graph effectiveness. Single-pass struct-only training, 1 h cap. “Baseline” uses degree only with no pairwise computation; “with Hawkeye ” adds k -core and the 2-hop cohesive bridge. Gain is in test-MRR points.
method
test MRR
TGN †
0.396
TGAT
0.508
DyGFormer (none)
0.537
GraphMixer
0.549
EdgeBank †
0.571
DyGFormer (cooccur)
0.779
Table 6. Comparison on tgbl-wiki (test MRR). † cited from the TGB leaderboard / original papers.
Figure 3. Per-dataset Hawkeye swap-in gain over the DyGFormer (cooccur) baseline (test AP for DGB, test MRR for wiki ); ★ = 3-seed validated (std ≤0.011 ). Double-digit gains on CanParl ( +10.8 ) and tgbl-subreddit ( +10.1 ), mid single-digit on mooc ( +5.8 ) and USLegis ( +4.8 ), small but consistent on sparse uci / enron ; on saturated reddit and degenerate tgbl-lastfm the gain correctly vanishes, tracking the training-free 2-hop discAUC predictor (§ 3 ).
dataset
2-hop discAUC
Hawkeye gain (pts)
reddit
0.98
≈0 (cooccur sat.) ★
tgbl-subreddit
0.96
+10.1★
mooc
0.94
+5.8★
tgbl-wiki
0.85
+2.8 (legacy)
tgbl-uci
0.76
+0.6★
tgbl-enron
0.73
+1.3★
Table 7. Training-free 2-hop discAUC (Table 1 ) vs. measured Hawkeye gain. Direct in the sparse/bipartite regimes; in the near-complete regime ( CanParl , USLegis ) the raw 2-hop count saturates but the trained, core-weighted Hawkeye still wins. ★ 3-seed mean ± std. tgbl-coin and UNvote have discAUC only (no trained gain) and are omitted.
Strategy
uci
mooc
reddit
baseline
1.00×
1.00×
1.00×
pinned + async
1.11×
1.00×
1.04×
prefetcher
1.21×
1.03×
1.07×
prefetch ×2
1.08×
1.00×
1.15×
precompute
3.47×
3.04×
3.16×
Table 8. Wall-clock speedup over the sequential baseline (three simulated epochs of 50 batches). Only precompute is universally robust.
configuration
time / epoch (s)
overhead
DyGFormer (none, no struct.)
5.4
−76%
DyGFormer (cooccur, baseline)
22.4
reference
DyGFormer + Hawkeye (gev, replace)
40.2
+79%
DyGFormer ⊕ Hawkeye (both, add)
57.1
+154%
Table 9. Measured per-epoch wall time on uci (3-seed mean). Overhead is relative to the DyGFormer baseline (cooccur).
Chair of Machine Learning for Complex Networks Center for Artificial Intelligence and Data Science (CAIDAS) Julius-Maximilians-Universität Würzburg, DE
M. Yu and Y.-g. Ha are with Smart Computing Laboratory, Department of Computer Science & Engineering, Konkuk University, Seoul 05029, Republic of Korea.