# Eric Wefald

**Eric Huang Wefald**, (died August 31, 1989) ^{[1]}

was an American computer scientist and researcher from University of California, Berkeley, California, who co-authored with Stuart Russell on multiple papers on search control, machine learning, and metareasoning, that is the process of reasoning about reasoning itself.
Eric Wefald obtained a Master of philosophy from Princeton in 1985, and was completing a doctorate in artificial intelligence at U.C. Berkeley, when he died in a car accident near Bordeaux, France, on August 31, 1989.

## Contents

# Decision-Theoretic Search Control

Abstract from Stuart Russell and Eric Wefald (**1988**). *Decision-Theoretic Search Control: General Theory and an Application to Game-Playing.* ^{[2]}:

In this paper we outline a general approach to the study of problem-solving, in which search steps are considered decisions in the same sense as actions in the world. Unlike other metrics in the literature, the value of a search step is defined as a real utility rather than as a quasi-utility, and can therefore be computed directly from a model of the base-level problem-solver. We develop a formula for the value of a search step in a game-playing context using the single-step assumption, namely that a computation step can be evaluated as it was the last to be taken. We prove some meta-level theorems that enable the development of a low- overhead algorithm, MGSS, that chooses search steps in order of highest estimated utility. Although we show that the single-step assumption is untenable in general, a program implemented for the game of Othello appears to rival an alpha-beta search with equal node allocations or time allocations. Pruning and search termination subsumes or improve on many other algorithms. Single-agent search, as in the A algorithm, yields a simpler analysis, and we are currently investigating applications of the algorithm developed for this case.

# Optimal Game-Tree Search

Abstract from Stuart Russell and Eric Wefald (**1989**). *On optimal game-tree search using rational metareasoning* ^{[3]}:

In this paper we outline a general approach to the study of problem-solving, in which search steps are considered decisions in the same sense as actions in the world. Unlike other metrics in the literature, the value of a search step is defined as a real utility rather than as a quasi-utility, and can therefore be computed directly from a model of the base-level problem-solver. We develop a formula for the expected value of a search step in a game-playing context using the single-step assumption, namely that a computation step can be evaluated as it was the last to be taken. We prove some meta-level theorems that enable the development of a low-overhead algorithm, MGSS*, that chooses search steps in order of highest estimated utility. Although we show that the single-step assumption is untenable in general, a program implemented for the game of Othello soundly beats an alpha-beta search while expanding significantly fewer nodes, even though both programs use the same evaluation function.

# Selected Publications

^{[4]} ^{[5]}

- Stuart Russell, Eric Wefald (
**1988**).*Decision-Theoretic Search Control: General Theory and an Application to Game-Playing.*CS Technical Report 88/435, University of California, Berkeley - Stuart Russell, Eric Wefald (
**1988**).*Multi-Level Decision-Theoretic Search.*AAAI Symposium on Computer Game-Playing, Stanford. - Stuart Russell, Eric Wefald (
**1989**).*On optimal game-tree search using rational metareasoning.*IJCAI 1989 - Eric Wefald, Stuart Russell (
**1989**).*Adaptive Learning of Decision-Theoretic Search Control Knowledge*. 6th International Workshop on Machine Learning - Stuart Russell, Eric Wefald (
**1991**).*Principles of Metareasoning.*Artificial Intelligence, Vol. 49, Nos. 1-3 - Stuart Russell, Eric Wefald (
**1991**).*Do the right thing: studies in limited rationality*. MIT Press

# References

- ↑ Princeton Alumni Weekly: Eric Huang Wefald, February 6, 1991
- ↑ Stuart Russell, Eric Wefald (
**1988**).*Decision-Theoretic Search Control: General Theory and an Application to Game-Playing.*CS Technical Report 88/435, University of California, Berkeley - ↑ Stuart Russell, Eric Wefald (
**1989**).*On optimal game-tree search using rational metareasoning.*IJCAI 1989 - ↑ DBLP: Eric Wefald
- ↑ Eric Wefald's research works | University of California, Berkeley, CA (UCB) and other places