## News on Intermediate Problems

* The Minimum Circuit Size Problem goes front and center *

Eric Allender, Bireswar Das, Cody Murray, and Ryan Williams have proved new results about problems in the range between and -complete. According to the wide majority view of complexity the range is vast, but it is populated by scant few natural computational problems. Only Factoring, Discrete Logarithm, Graph Isomorphism (GI), and the Minimum Circuit Size Problem (MCSP) regularly get prominent mention. There are related problems like group isomorphism and others in subjects such as lattice-based cryptosystems. We covered many of them some years back.

Today we are delighted to report recent progress on these problems.

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## The Right Stuff of Emptiness

* How ∅ versus {ε} can be a life-and-death difference*

Cropped from source |

Jeff Skiles was the co-pilot on US Airways Flight 1549 from New York’s LaGuardia Airport headed for Charlotte on January 15, 2009. The Airbus A320 lost power in both engines after striking birds at altitude about 850 meters and famously ditched in the Hudson River with no loss of life. As Skiles’s website relates, he had manual charge of the takeoff but upon his losing his instrument panel when the engines failed,

“Captain Chesley Sullenberger took over flying the plane and tipped the nose down to retain airspeed.”

Skiles helped contact nearby airports for emergency landing permission but within 60 seconds Sullenberger and he determined that the Hudson was the only option. His front page does not say he did anything else.

Today we tell some stories about the technical content of forms of emptiness.

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## Ada the Amplifier

* Plus updated links to our Knuth and TED talks *

Ada Lovelace was nuts. Some have used this to minimize her contributions to the stalled development of Charles Babbage’s “Analytical Engine” in the 1840s. Judging from her famously over-the-top “Notes” to her translation of the only scientific paper (known as the “Sketch”) published on Babbage’s work in his lifetime, we think the opposite. It took nuttily-driven intensity to carry work initiated by Babbage several square meters of print beyond what he evidently bargained for.

This month we have been enjoying Walter Isaacson’s new book *The Innovators*, which leads with her example, and have some observations to add.

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## Still A Brilliant Idea

* An apology and correction *

Cynthia Dwork, Frank McSherry, Kobbi Nissim, and Adam Smith are the inventors of differential privacy, as formulated in their 2006 paper “Calibrating Noise to Sensitivity in Private Data Analysis,” in the proceedings of the 2006 Theory of Cryptography Conference.

Today Ken and I want to talk about differential privacy again.

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## Cynthia Dwork and a Brilliant Idea

* Differential Privacy *

Taekwondo source |

Cynthia Dwork is a computer scientist who is a Distinguished Scientist at Microsoft Research. She has done great work in many areas of theory, including security and privacy.

Today Ken and I wish to talk about the notion of differential privacy and Dwork’s untiring advocacy of it.

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## Where Hard Meets Easy

* Some hard to compute functions are easy modulo a number *

Georgia Tech source |

Joseph Ford was a physicist at Georgia Tech. He earned his undergrad degree here in 1952, and after earning his PhD at Johns Hopkins, went to work for two years at Union Carbide in Niagara Falls before joining the University of Miami and then coming back to Tech. He was possibly lured back into academia by considering a paradox studied by Enrico Fermi, John Pasta, Stanislaw Ulam, and Mary Tsingou in the mid-1950s. The paradox is that periodic rather than ergodic motion can often result in complicated systems.

Today we wish to present a simple observation about hard-to-compute functions.

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## Why is Congruence Hard to Learn?

* Gears and rings… *

Flickr source: |

Denys Fisher was a British engineer and maker of board games and other toys. In 1965 he invented the Spirograph toy. Some speculate that he was influenced by the designs of the artist, composer, and film animator John Whitney, whose opening sequence for Alfred Hitchcock’s 1958 film “Vertigo” is considered the first use of computer graphics in cinema. The Spirograph toy involves drawing with a pen guided by a gear with *m* teeth going around inside a ring or around a track or other gear with *x* teeth. The kind of design you get depends on how *x* relates to *m*.

Today Ken and I want to talk about a basic notion of mathematics and theory that is simple to define, very useful, and yet seems to be tough for some students to get.

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