Christopher Tidy was 10 years old the first time he took apart an engine. The carburetor--the block of machinery that supplies a gas engine with fuel and air and helps to spark ignition--was a mess. It was blocked with thick layers of congealed fuel and dust. Tidy saw the problem and just happened to have some tools nearby and a burning curiosity about how exactly this thing worked and what he could do to fix it. That quickly turned into an attempt "to assemble a kind of Frankenstein engine" out of the parts of many discarded petrol engines. He disassembled the rumbling machine piece by piece until he found the offending parts, then doused the carburetor in gasoline, followed by water and dish soap, then scrubbed it clean with a toothbrush.

Whether it's pet hair or unexplainable debris, nothing sends me into a rage quite like dirty floors. If you've got a similar attitude towards dirt, then you're in luck, as we've got an awesome deal on a robot vacuum today. Amazon's selling the Shark AI Ultra Voice Control Robot Vacuum for $298, which is 50 percent off of the original $599 price. Not only does this vacuum empty itself, but it also has a self-cleaning brushroll, which means you don't have to deal with tangled up hair and other nasty bits. The Shark AI Ultra works on hard floors and carpets and has precision home mapping.

There are so many devices these days that make our lives remarkably easier, but one of the best has to be the robot vacuum. It gets under the couch more easily and you don't have to set aside time to tidy up the floor. Right now, you can jump into the cleanest part of the smart home revolution for a little bit less. Amazon has a one-day sale on Eufy's Anker robot vacuums. The deals end just before midnight Pacific time on Wednesday evening. The best deal today is the Anker RoboVac X8 Hybrid, which is on sale for $400.

If you don't have a robot vacuum yet, you're missing out on all that hands-free cleaning time. Today, however, you can jump into the autonomous floor cleaning revolution at a good price. Amazon has a one-day sale on Ecovacs robot vacuums. The deal includes just two models, but both are popular options. The sale ends just before midnight Pacific time on Thursday evening.

Wickham and Grolemund have produced an excellent book that would help a beginning R user become very efficient in explanatory analysis. Unsurprisingly the approach that they expound utilises the "hadleyverse" a collection of packages (ggplot2 for visualisation, tidyr for reshaping, dplyr for selecting and filtering, purrr for functional programming, broom for linear models etc) that dramatically speed up most of the common steps involved in an analysis. One benefit of Wickham's involvement in these packages has been a coherent philosophy that sits behind them. It can be a little tricky when learning this philosophy, but the long term benefits are enormous. The book is broken up into a number of sections that effectively builds up the ability to ingest, transform, visualise and model datasets.

Although planning for the tasks a household robot has to perform appears to be easy, there exists the problem that the robot is usually uncertain about the state of the household when starting to plan. For example, when getting the order of tidying up the kitchen, the robot does not know what objects it will have to put away and whether there are actually any objects that need to be put away. Furthermore, while sensing operations can provide moreinformation about the environment, things can go wrong when executingan action. In this paper, we try to identify conditions under which classical planning can be used in a replanning loop in order to solve the planning problem in nondeterministic partially observable open domains. In particular, we will define completeness and soundness of replanning with respect to nondeterministic planning and we will identify a PSPACE-checkable condition that guarantees soundness.