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Steven Spencer

Publications and source records attributed to Steven Spencer.

4 recordsLinked to original sources

TacticGen: Grounding Adaptable and Scalable Generation of Football Tactics

Success in association football relies on both individual skill and coordinated tactics. While recent advancements in spatio-temporal data and deep learning have enabled predictive analyses like trajectory forecasting, the development of tactical design remains limited. Bridging this gap is essential, as prediction reveals what is likely to occur, whereas tactic generation determines what should occur to achieve strategic objectives. In this work, we present TacticGen, a generative model for adaptable and scalable tactic generation. TacticGen formulates tactics as sequences of multi-agent movements and interactions conditioned on the game context. It employs a multi-agent diffusion transformer with agent-wise self-attention and context-aware cross-attention to capture cooperative and competitive dynamics among players and the ball. Trained with over 3.3 million events and 100 million tracking frames from top-tier leagues, TacticGen achieves state-of-the-art precision in predicting player trajectories. Building on it, TacticGen enables adaptable tactic generation tailored to diverse inference-time objectives through classifier guidance mechanism, specified via rules, natural language, or neural models. Its modeling performance is also inherently scalable. A case study with football experts confirms that TacticGen generates realistic, strategically valuable tactics, demonstrating its practical utility for tactical planning in professional football. The project page is available at: https://shengxu.net/TacticGen/.

cs.AI

Absence of Translational Ordering in Driven Vortex Lattices

By using finite temperature molecular dynamics simulations, we consider the question of the existence of dynamical ordering as a two dimensional vortex lattice is driven through a random background potential. The shape of the current-voltage(I-V) characteristics are qualitatively the same as those seen in experiments on the conventional superconductors 2H-NbSe_{2} and Mo_{77}Ge_{23}. However, in contrast to previous simulations, we find that the lattice has no topological or translational order for any value of the driving but that it does exhibit a high driving phase where long range orientational order exists.

cond-mat.supr-con

The Bean Critical State: Infinitely Unstable

The threshold for creep in the Bean critical state is investigated. We perturb the Bean state by an energy $Δε$. We find that no matter how small $Δε$ is it will always be able to induce creep somewhere on the Bean profile. This finding has important consequences for the interpretation of low temperature creep phenomena in terms of quantum creep.

supr-con

Elastic Chain in a Random Potential: Simulation of the Displacement Function $<(u(x)-u(0))^2>$ and Relaxation

We simulate the low temperature behaviour of an elastic chain in a random potential where the displacements $u(x)$ are confined to the {\it longitudinal} direction ($u(x)$ parallel to $x$) as in a one dimensional charge density wave--type problem. We calculate the displacement correlation function $g(x)=< (u(x)-u(0))^2>$ and the size dependent average square displacement $W(L)=<(u(x)-\bar{u})^2>$. We find that $g(x)\sim x^{2η}$ with $η\simeq3/4$ at short distances and $η\simeq3/5$ at intermediate distances. We cannot resolve the asymptotic long distance dependence of $g$ upon $x$. For the system sizes considered we find $g(L/2)\propto W\sim L^{2χ}$ with $χ\simeq2/3$. The exponent $η\simeq3/5$ is in agreement with the Random Manifold exponent obtained from replica calculations and the exponent $χ\simeq2/3$ is consistent with an exact solution for the chain with {\it transverse} displacements ($u(x)$ perpendicular to $x$).The distribution of nearest distances between pinning wells and chain-particles is found to develop forbidden regions.

cond-mat