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Comment: Not surprising (Score 1) 212

by larsbars (#39150851) Attached to: Physics Is (NP-)Hard

given this:

Unpredictability and undecidability in dynamical systems

Abstract: "We show that motion with as few as three degrees of freedom (for instance, a particle moving in a three-dimensional potential) can be equivalent to a Turing machine, and so be capable of universal computation. Such systems possess a type of unpredictability qualitatively stronger than that which has been previously discussed in the study of low-dimensional chaos: Even if the initial conditions are known exactly, virtually any question about their long-term dynamics is undecidable."

Comment: Re:Ham Sandwich Theorem (Score 1) 170

by larsbars (#35319040) Attached to: Erdos' Combinatorial Geometry Problem Solved

If you cut a body by a plane through its center of gravity you _do not_ necessarily have equal volumes on either side of the plane.

He didn't say you have equal volumes. He said you have equal masses.

Cutting a body through it's center of mass doesn't still doesn't necessarily leave equal masses on either side of the (hyper-)plane. The center of mass lets you ignore the distribution of mass as a function of position (density) for certain types of problems. This is not one of them. What you are saying is still trivial, still wrong, and still not the ham sandwich theorem.

Comment: Re:Ham Sandwich Theorem (Score 1) 170

by larsbars (#35315264) Attached to: Erdos' Combinatorial Geometry Problem Solved
What you call the Ham Sandwich Theorem is true, trivial, and most definitely _not_ the Ham Sandwich Theorem. The theorem states that there is a plane that has equal portions of ham and of each slice of bread on either side. If you cut a body by a plane through its center of gravity you _do not_ necessarily have equal volumes on either side of the plane.
Handhelds

+ - good PDF reader device with internet browsing? 2

Submitted by ranjix
ranjix (892606) writes "Hello everybody. I ask the collective intelligence to help me with this one. I need a handheld device which would allow me to read ebooks and/or browse the internet while actively and intensely laying in the hammock (and yes, I do have a hammock in my mom's basement). I'll try to sum the basic requirements: (good) PDF reader (and ebooks of whatever sort), WiFi connectivity and Internet browser, screen minimum 4.5", readable in sunlight etc, fairly responsive, at least 4-5 hours battery. Obviously I looked at the usual suspects: Kindle/Amazon tries to grab one into the proprietary formats and their own network (while other ebook readers don't really browse the internet), laptops/netbooks are pretty hard to hold, and the UMPC arena seems a hodge-podge of "to be released" (Viliv S5? Aigo whatever?) with "seriously expensive" (Sony, OQO) or plain "we recommend you don't buy" (Samsung Q1Ex). Is there anything else I could use in given circumstances?
Appreciate,
ranjix"
Networking

Researchers Apply P2P Principles To Car Traffic 111

Posted by ScuttleMonkey
from the traffic-eagle-eye dept.
alphadogg writes to tell us that lessons learned from peer-to-peer networks are being applied to traffic systems in order to prevent jams. "Their Autonet plan would center around ad hoc networks of vehicles and roadside monitoring posts supported by 802.11 technology (the prototype uses 11b). The vehicles would essentially be the 'clients' in such a system and feature graphical user interfaces to pass along information to drivers. They're building the system to be able to handle data on thousands of traffic incidents and road conditions."

"Those who will be able to conquer software will be able to conquer the world." -- Tadahiro Sekimoto, president, NEC Corp.

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