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Sabbath mode, also known as Shabbos mode (Ashkenazi pronunciation) or Shabbat mode, is a feature in many modern home appliances, including ovens and refrigerators, which is intended to allow the appliances to be used (subject to various constraints) by Shabbat-observant Jews on the Shabbat and Jewish holidays. The mode usually overrides the usual, everyday operation of the electrical appliance and makes the operation of the appliance comply with the rules of Halakha (Jewish law).

A recursive island or lake is an island or lake that is itself within an island or lake.

The curse of dimensionality refers to various phenomena that arise when analyzing and organizing data in high-dimensional spaces (often with hundreds or thousands of dimensions) that do not occur in low-dimensional settings such as the three-dimensional physical space of everyday experience. The expression was coined by Richard E. Bellman when considering problems in dynamic programming.

Cursed phenomena occur in domains such as numerical analysis, sampling, combinatorics, machine learning, data mining and databases. The common theme of these problems is that when the dimensionality increases, the volume of the space increases so fast that the available data become sparse. This sparsity is problematic for any method that requires statistical significance. In order to obtain a statistically sound and reliable result, the amount of data needed to support the result often grows exponentially with the dimensionality. Also, organizing and searching data often relies on detecting areas where objects form groups with similar properties; in high dimensional data, however, all objects appear to be sparse and dissimilar in many ways, which prevents common data organization strategies from being efficient.

The superformula is a generalization of the superellipse and was proposed by Johan Gielis around 2000. Gielis suggested that the formula can be used to describe many complex shapes and curves that are found in nature. Gielis has filed a patent application related to the synthesis of patterns generated by the superformula.

In polar coordinates, with ${\displaystyle r}$ the radius and ${\displaystyle \varphi }$ the angle, the superformula is:

${\displaystyle r\left(\varphi \right)=\left(\left|{\frac {\cos \left({\frac {m_{1}\varphi }{4}}\right)}{a}}\right|^{n_{2}}+\left|{\frac {\sin \left({\frac {m_{2}\varphi }{4}}\right)}{b}}\right|^{n_{3}}\right)^{-{\frac {1}{n_{1}}}}.}$

By choosing different values for the parameters ${\displaystyle a,b,m_{1},m_{2},n_{1},n_{2},}$ and ${\displaystyle n_{3},}$ different shapes can be generated.

The formula was obtained by generalizing the superellipse, named and popularized by Piet Hein, a Danish mathematician.

The sand cat (Felis margarita), also known as the sand dune cat, is the only cat living chiefly in true deserts. This small cat is widely distributed in the deserts of North Africa, the Middle East and Central Asia. Starting in 2002, it was listed as near threatened on the IUCN Red List because the population was considered fragmented and small with a declining trend. It was downlisted to least concern in 2016.

Owing to long hairs covering the soles of its feet, the sand cat is well adapted to the extremes of a desert environment and tolerant of extremely hot and cold temperatures. It inhabits both sandy and stony deserts, in areas far from water sources.

Electrochemical Random-Access Memory (ECRAM) is a type of non-volatile memory (NVM) with multiple levels per cell (MLC) designed for deep learning analog acceleration. An ECRAM cell is a three-terminal device composed of a conductive channel, an insulating electrolyte, an ionic reservoir, and metal contacts. The resistance of the channel is modulated by ionic exchange at the interface between the channel and the electrolyte upon application of an electric field. The charge-transfer process allows both for state retention in the absence of applied power, and for programming of multiple distinct levels, both differentiating ECRAM operation from that of a field-effect transistor (FET). The write operation is deterministic and can result in symmetrical potentiation and depression, making ECRAM arrays attractive for acting as artificial synaptic weights in physical implementations of artificial neural networks (ANN). The technological challenges include open circuit potential (OCP) and semiconductor foundry compatibility associated with energy materials. Universities, government laboratories, and corporate research teams have contributed to the development of ECRAM for analog computing. Notably, Sandia National Laboratories designed a lithium-based cell inspired by solid-state battery materials, Stanford University built an organic proton-based cell, and International Business Machines (IBM) demonstrated in-memory selector-free parallel programming for a logistic regression task in an array of metal-oxide ECRAM designed for insertion in the back end of line (BEOL). In 2022, researchers at Massachusetts Institute of Technology built an inorganic, CMOS-compatible protonic technology that achieved near-ideal modulation characteristics using nanosecond fast pulses

The Kearny fallout meter, or KFM, is an expedient radiation meter. It is designed such that someone with a normal mechanical ability would be able to construct it before or during a nuclear attack, using common household items.

The Kearny fallout meter was developed by Cresson Kearny from research performed at Oak Ridge National Laboratory and published in the civil defense manual Nuclear War Survival Skills (ISBN 0-942487-01-X). The plans were originally released in Oak Ridge National Laboratory publication ORNL-5040, The KFM, A Homemade Yet Accurate and Dependable Fallout Meter and have been formatted in a newsprint-ready layout so that they may be quickly printed with accurate dimensions in local newspapers. It must be built from a correctly scaled copy of the plans; photocopies and printouts of digital copies may not be to scale.

The 996 working hour system (Chinese: 996工作制) is a work schedule commonly practiced by some companies in the People's Republic of China. It derives its name from its requirement that employees work from 9:00 am to 9:00 pm, 6 days per week; i.e. 72 hours per week. A number of Chinese internet companies have adopted this system as their official work schedule. Critics argue that the 996 working hour system is a flagrant violation of Chinese law.

In March 2019 an "anti-996" protest was launched via GitHub.

In computational complexity and optimization the no free lunch theorem is a result that states that for certain types of mathematical problems, the computational cost of finding a solution, averaged over all problems in the class, is the same for any solution method. The name alludes to the saying "no such thing as a free lunch", that is, no method offers a "short cut". This is under the assumption that the search space is a probability density function. It does not apply to the case where the search space has underlying structure (e.g., is a differentiable function) that can be exploited more efficiently (e.g., Newton's method in optimization) than random search or even has closed-form solutions (e.g., the extrema of a quadratic polynomial) that can be determined without search at all. For such probabilistic assumptions, the outputs of all procedures solving a particular type of problem are statistically identical. A colourful way of describing such a circumstance, introduced by David Wolpert and William G. Macready in connection with the problems of search and optimization, is to say that there is no free lunch. Wolpert had previously derived no free lunch theorems for machine learning (statistical inference). Before Wolpert's article was published, Cullen Schaffer independently proved a restricted version of one of Wolpert's theorems and used it to critique the current state of machine learning research on the problem of induction.

In the "no free lunch" metaphor, each "restaurant" (problem-solving procedure) has a "menu" associating each "lunch plate" (problem) with a "price" (the performance of the procedure in solving the problem). The menus of restaurants are identical except in one regard – the prices are shuffled from one restaurant to the next. For an omnivore who is as likely to order each plate as any other, the average cost of lunch does not depend on the choice of restaurant. But a vegan who goes to lunch regularly with a carnivore who seeks economy might pay a high average cost for lunch. To methodically reduce the average cost, one must use advance knowledge of a) what one will order and b) what the order will cost at various restaurants. That is, improvement of performance in problem-solving hinges on using prior information to match procedures to problems.

In formal terms, there is no free lunch when the probability distribution on problem instances is such that all problem solvers have identically distributed results. In the case of search, a problem instance in this context is a particular objective function, and a result is a sequence of values obtained in evaluation of candidate solutions in the domain of the function. For typical interpretations of results, search is an optimization process. There is no free lunch in search if and only if the distribution on objective functions is invariant under permutation of the space of candidate solutions. This condition does not hold precisely in practice, but an "(almost) no free lunch" theorem suggests that it holds approximately.

An autopen or signing machine is a device used for the automatic signing of a signature or autograph. Many celebrities, politicians and public figures receive hundreds of letters a day, many of which request a personal reply; this leads to a situation in which either the individual must artificially reproduce their signature or heavily limit the number of recipients who receive a personal response. Given the exact verisimilitude to the real hand signature, the use of the autopen allows for a small degree of wishful thinking and plausible deniability as to whether a famous autograph is real or reproduced, thus increasing the perception of the personal value of the signature by the lay recipient. However, known or suspected autopen signatures are also vastly less valuable as philographic collectibles; legitimate hand-signed documents from individuals known to also use an autopen usually require verification and provenance to be considered valid.

The early autopens used a plastic matrix of the original signature which is a channel cut into an engraved plate in the shape of a wheel. A stylus driven by an electric motor followed the x and y axis of a profile or shape engraved in the plate (which is why it is called a matrix). The stylus is mechanically connected to an arm which can hold almost any common writing instrument, so the favourite pen and ink can be used to suggest authenticity. The Autopen signature is made with even pressure (and indentation in the paper), which is how these machines are distinguishable from original handwriting where the pressure varies.

Modern day autopens use a signature smart card or USB flash drive to store signatures and phrases instead of the plastic matrices. In addition, certain models can replicate entire pages of writing once a custom font has been created in a user's handwriting.