editor’s letter

DOI: 10.1145/1629175.1629176
Moshe Y. Vardi

more Debate, Please!

In the May 1979 issue of Communications,

a powerfully written article by Richard A.

De Millo, Richard J. Lipton, and Alan J. Perlis

entitled “Social Processes and Proofs

of Theorems and Programs,” argued

that formal verification of programs is

“difficult to justify and manage.” The

article created the perception, in the

minds of many computer scientists,

that formal verification is a futile area

of computing research.

That article did not cite a 1977 pa-

per by Amir Pnueli entitled “The Tem-

poral Logic of Programs.” His paper

had attracted little attention by 1979,

but by 1997 it would be described as a

“landmark paper” in the citation that

accompanied Pnueli’s 1996 ACM A.M.

Turing Award. In his paper, Pnueli,

whose sudden and unexpected death

on Nov. 2, 2009 shocked the computer

science community, laid the founda-

tion for formal verification of concur-

rent and reactive programs. (An article

describing Pnueli’s scientific legacy ap-

pears on page 22.) The paper also laid

the foundation for the development of

model checking, an automated formal-

verification technique for which Ed-

mund A. Clarke, E. Allen Emerson, and

Joseph Sifakis received the 2007 ACM

Turing Award.

With hindsight of 30 years, it seems

that De Millo, Lipton, and Perlis’ arti-

cle has proven to be rather misguided.

In fact, it is interesting to read it now

and see how arguments that seemed

so compelling in 1979 seem so off the

mark today. Should we infer that Com-

munications erred in publishing that ar-

ticle? My answer is a resounding “no!”

My basic education included expo-

sure to Talmudic scholarship. Jewish

scholars in the first half of the first mil-

lennium believed that truth will emerge

from vigorous debate. The Talmud, a

monumental work of Jewish scholar-

ship concluded circa 500 CE, is in es-

sence a compendium of legal debates.

Vigorous debate, I believe, exposes all

sides of an issue—their strengths and

weaknesses. It helps us to reach more

knowledgable conclusions. To quote

Benjamin Franklin: “When Truth and

Error have fair Play, the former is always

an overmatch for the latter.” In my opin-

ion, however, the editors of Commu-

nications in 1979 did err in publishing

an article that can fairly be described

as tendentious without publishing a

counterpoint article in the same issue.

Indeed, the article instigated so many

reader responses, the editors published

10 pages of letters in the November

1979 Forum section of Communica-

tions, calling the work everything from

“marvelous” to “humorous.”

In 2007, when I met with various fo-

cus groups to discuss the relaunching

of Communications, I was encouraged to

keep this publication engaged in con-

troversial topics. “Let blood spill over

the pages of Communications,” said one

discussant jokingly. At the same time,

however, participants believed that the

magazine should represent all points of

view fairly. This sentiment led to the es-

tablishment of the Point-Counterpoint

feature, in which both sides of an issue

are represented by opposing articles.

Quoting Franklin again: “when Men

differ in Opinion, both Sides ought

equally to have the Advantage of being

heard by the Publick.”

Since the relaunch in July 2008, we

have published several Point-Counter-

point pairs: on computing curricula,

e-voting, Net neutrality, and the direc-

tion of CS education in the U.S. At this

point, however, the pipeline for such

articles is dry. I had assumed that both

members of the editorial board and

readers would propose topics for Point-

Counterpoint articles, but that does

not seem to be the case. It is almost as

if people believe there is something im-

proper about engaging in direct debate.

In fact, several authors whom I invited

to participate in Point-Counterpoint

debates have declined in order to avoid

head-on confrontation. The truth is,

however, that there are many issues in

computing that inspire differing opin-

ions. We would be better off highlight-

ing the differences rather than pretend-

ing they do not exist.

In this issue of Communications we

have a debate that is quite a rarity in

computing research: a technical de-

bate. MapReduce (MR) is a software

framework to support distributed com-

puting on large data sets on computer

clusters. It was introduced by J. Dean

and S. Ghemawat of Google in a highly

influential 2004 article, and featured

as a Research Highlight paper in the

January 2008 issue of Communications.

The success of MapReduce led some

to claim that the extreme scalability of

MR will “relegate relational database

management systems (RDBMS) to the

status of legacy technology.” A pair of

Contributed Articles in this issue—

Dean and Ghemwat on one side and

Stonebraker et al. on the other—debate

the relative merits of MR and RDBMS

beginning on page 64. As parallel com-

putation is one of the hottest topics in

computing today, I have no doubt that

our readers will find this technical de-

bate highly instructive.

If you have topics that you think

should be debated on the pages of

Communications, please contact me.

More debate, please!

Moshe Y. Vardi, EDItoR-In-CHIEf