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🔗 Computing 🔗 Computer science 🔗 Computing/Computer science

This article is a list of notable unsolved problems in computer science. A problem in computer science is considered unsolved when no solution is known, or when experts in the field disagree about proposed solutions.

In machine learning, the kernel embedding of distributions (also called the kernel mean or mean map) comprises a class of nonparametric methods in which a probability distribution is represented as an element of a reproducing kernel Hilbert space (RKHS). A generalization of the individual data-point feature mapping done in classical kernel methods, the embedding of distributions into infinite-dimensional feature spaces can preserve all of the statistical features of arbitrary distributions, while allowing one to compare and manipulate distributions using Hilbert space operations such as inner products, distances, projections, linear transformations, and spectral analysis. This learning framework is very general and can be applied to distributions over any space ${\displaystyle \Omega }$ on which a sensible kernel function (measuring similarity between elements of ${\displaystyle \Omega }$) may be defined. For example, various kernels have been proposed for learning from data which are: vectors in ${\displaystyle \mathbb {R} ^{d}}$, discrete classes/categories, strings, graphs/networks, images, time series, manifolds, dynamical systems, and other structured objects. The theory behind kernel embeddings of distributions has been primarily developed by Alex Smola, Le Song , Arthur Gretton, and Bernhard Schölkopf. A review of recent works on kernel embedding of distributions can be found in.

The analysis of distributions is fundamental in machine learning and statistics, and many algorithms in these fields rely on information theoretic approaches such as entropy, mutual information, or Kullback–Leibler divergence. However, to estimate these quantities, one must first either perform density estimation, or employ sophisticated space-partitioning/bias-correction strategies which are typically infeasible for high-dimensional data. Commonly, methods for modeling complex distributions rely on parametric assumptions that may be unfounded or computationally challenging (e.g. Gaussian mixture models), while nonparametric methods like kernel density estimation (Note: the smoothing kernels in this context have a different interpretation than the kernels discussed here) or characteristic function representation (via the Fourier transform of the distribution) break down in high-dimensional settings.

Methods based on the kernel embedding of distributions sidestep these problems and also possess the following advantages:

1. Data may be modeled without restrictive assumptions about the form of the distributions and relationships between variables
2. Intermediate density estimation is not needed
3. Practitioners may specify the properties of a distribution most relevant for their problem (incorporating prior knowledge via choice of the kernel)
4. If a characteristic kernel is used, then the embedding can uniquely preserve all information about a distribution, while thanks to the kernel trick, computations on the potentially infinite-dimensional RKHS can be implemented in practice as simple Gram matrix operations
5. Dimensionality-independent rates of convergence for the empirical kernel mean (estimated using samples from the distribution) to the kernel embedding of the true underlying distribution can be proven.
6. Learning algorithms based on this framework exhibit good generalization ability and finite sample convergence, while often being simpler and more effective than information theoretic methods

Thus, learning via the kernel embedding of distributions offers a principled drop-in replacement for information theoretic approaches and is a framework which not only subsumes many popular methods in machine learning and statistics as special cases, but also can lead to entirely new learning algorithms.

🔗 Books 🔗 Systems 🔗 Business 🔗 Psychology 🔗 United Kingdom 🔗 Engineering 🔗 Invention 🔗 Systems/Project management 🔗 Method engineering

Six Thinking Hats was written by Dr. Edward de Bono. "Six Thinking Hats" and the associated idea parallel thinking provide a means for groups to plan thinking processes in a detailed and cohesive way, and in doing so to think together more effectively.

In 2005, the tool found some use in the United Kingdom innovation sector, where it was offered by some facilitation companies and had been trialled within the United Kingdom's civil service.

🔗 Military history 🔗 Disaster management 🔗 Military history/Military aviation 🔗 Telecommunications 🔗 Computer Security 🔗 Computer Security/Computing 🔗 Syria 🔗 Israel 🔗 Military history/Middle Eastern military history 🔗 Explosives 🔗 Military history/Post-Cold War 🔗 Lebanon

On 17 September 2024, communication pagers simultaneously exploded across Lebanon and Syria in an apparent coordinated attack. Many of the pagers were owned by members of the Hezbollah militant group. Eighteen people were confirmed killed: eleven in Lebanon (including a child and at least two Hezbollah members) and seven in Syria. Around 4,000 people were reportedly injured, including Hezbollah members and civilians.

The blasts affected several Hezbollah strongholds, including Beirut's Dahieh suburb, southern Lebanon, and in the Beqaa Valley. Over 500 of the group's militants lost their eyesight. They called the incident the organization's "biggest security breach yet" and accused Israel of responsibility.

A day after Hamas launched its October 7 attacks on Israel in 2023, the Iranian-backed organization Hezbollah joined the conflict in support of Hamas by firing on Israel. This led to a series of cross-border military exchanges between Hezbollah and Israel. In February 2024, the secretary-general of Hezbollah, Hassan Nasrallah, told the group's members to use pagers instead of cell phones, claiming that Israel had infiltrated their cell phone network. Hezbollah then bought a new brand of pagers that were recently imported to Lebanon.

Earlier on the day of the explosion, Israel's domestic security agency, the Shin Bet, announced it had thwarted a Hezbollah plot to assassinate a former senior defense official using an explosive device.

Around 150 hospitals across Lebanon received victims of the attack, which saw chaotic scenes.

🔗 Architecture 🔗 Urban studies and planning 🔗 Effective Altruism

The YIMBY movement (short for "yes in my back yard") is a pro-infrastructure development movement mostly focusing on public housing policy, real estate development, public transportation, and pedestrian safety in transportation planning, in contrast and in opposition to the NIMBY ("not in my back yard") movement that generally opposes most forms of urban development in order to maintain the status quo. As a popular organized movement in the United States, it began in the San Francisco Bay Area in the 2010s amid a major housing affordability crisis and has subsequently become a potent political force in state and local politics across the United States.

The YIMBY position supports increasing the supply of housing within cities where housing costs have escalated to unaffordable levels. They have also supported infrastructure development projects like improving housing development (especially for affordable housing or trailer parks), high-speed rail lines, homeless shelters, day cares, schools, universities and colleges, bike lanes, and transportation planning that promotes pedestrian safety infrastructure. YIMBYs often seek rezoning that would allow denser housing to be produced or the repurposing of obsolete buildings, such as shopping malls, into housing. Some YIMBYs have also supported public-interest projects like clean energy or alternative transport.

The YIMBY movement has supporters across the political spectrum, including left-leaning adherents who believe housing production is a social justice issue, free-market libertarian proponents who think the supply of housing should not be regulated by the government, and environmentalists who believe land use reform will slow down exurban development into natural areas. YIMBYs argue cities can be made increasingly affordable and accessible by building more infill housing,^: 1 and that greenhouse gas emissions will be reduced by denser cities.

🔗 Professional sound production 🔗 Record Production 🔗 The Beatles 🔗 Pop music

The Wall of Sound (also called the Spector Sound) is a music production formula developed by American record producer Phil Spector at Gold Star Studios, in the 1960s, with assistance from engineer Larry Levine and the conglomerate of session musicians later known as "the Wrecking Crew". The intention was to exploit the possibilities of studio recording to create an unusually dense orchestral aesthetic that came across well through radios and jukeboxes of the era. Spector explained in 1964: "I was looking for a sound, a sound so strong that if the material was not the greatest, the sound would carry the record. It was a case of augmenting, augmenting. It all fit together like a jigsaw."

A popular misconception holds that the Wall of Sound was created simply through a maximum of noise and distortion, but the method was actually more nuanced. To attain the Wall of Sound, Spector's arrangements called for large ensembles (including some instruments not generally used for ensemble playing, such as electric and acoustic guitars), with multiple instruments doubling or tripling many of the parts to create a fuller, richer tone. For example, Spector often duplicated a part played by an acoustic piano with an electric piano and a harpsichord. Mixed well enough, the three instruments would then be indistinguishable to the listener.

Among other features of the sound, Spector incorporated an array of orchestral instruments (strings, woodwind, brass and percussion) not previously associated with youth-oriented pop music. Reverb from an echo chamber was also highlighted for additional texture. He characterized his methods as "a Wagnerian approach to rock & roll: little symphonies for the kids". The combination of large ensembles with reverberation effects also increased the average audio power in a way that resembles compression. By 1979, the use of compression had become common on the radio, marking the trend that led to the loudness war in the 1980s.

The intricacies of the technique were unprecedented in the field of sound production for popular music. According to Beach Boys leader Brian Wilson, who used the formula extensively: "In the '40s and '50s, arrangements were considered 'OK here, listen to that French horn' or 'listen to this string section now.' It was all a definite sound. There weren't combinations of sound and, with the advent of Phil Spector, we find sound combinations, which—scientifically speaking—is a brilliant aspect of sound production."

🔗 Computer science

In computer science, higher-order abstract syntax (abbreviated HOAS) is a technique for the representation of abstract syntax trees for languages with variable binders.

🔗 United States 🔗 Biography 🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 United States/Military history - U.S. military history 🔗 Military history/Military biography 🔗 Biography/military biography 🔗 Military history/World War II 🔗 Military history/Cold War 🔗 United States/Texas 🔗 Biography/Actors and Filmmakers 🔗 Biography/Musicians 🔗 Westerns 🔗 Westerns/Biography

Audie Leon Murphy (20 June 1925 – 28 May 1971) was an American soldier, actor, and songwriter. He was widely celebrated as the most decorated American combat soldier of World War II, and has been described as the most highly decorated soldier in U.S. history. He received every military combat award for valor available from the United States Army, as well as French and Belgian awards for heroism. Murphy received the Medal of Honor for valor that he demonstrated at the age of 19 for single-handedly holding off a company of German soldiers for an hour at the Colmar Pocket in France in January 1945, before leading a successful counterattack while wounded and out of ammunition.

Murphy was born into a large family of sharecroppers in Hunt County, Texas. After his father abandoned them, his mother died when he was a teenager. Murphy left school in fifth grade to pick cotton and find other work to help support his family; his skill with a hunting rifle helped feed his family.

After the attack on Pearl Harbor in 1941, Murphy's older sister helped him to falsify documentation about his birthdate in order to meet the minimum age requirement for enlisting in the military. Turned down initially for being underweight by the Army, Navy, and the Marine Corps, he eventually was able to enlist in the Army. He first saw action in the 1943 Allied invasion of Sicily; then in 1944 he participated in the Battle of Anzio, the liberation of Rome, and the invasion of southern France. Murphy fought at Montélimar and led his men on a successful assault at L'Omet quarry near Cleurie in northeastern France in October. Despite suffering from multiple illnesses and wounds throughout his service, Murphy became one of the most praised and decorated soldiers of World War II. He is credited with killing 241 enemy soldiers.

After the war, Murphy embarked on a 21-year acting career. He played himself in the 1955 autobiographical film To Hell and Back, based on his 1949 memoirs of the same name, but most of his roles were in Westerns. He made guest appearances on celebrity television shows and starred in the series Whispering Smith. Murphy was a fairly accomplished songwriter. He bred quarter horses in California and Arizona, and became a regular participant in horse racing.

Because Murphy had what would today be described as post-traumatic stress disorder (PTSD), then known as "battle fatigue", he slept with a loaded handgun under his pillow. He looked for solace in addictive sleeping pills. In his last few years, he was plagued by money problems but refused offers to appear in alcohol and cigarette commercials because he did not want to set a bad example. Murphy died in a plane crash in Virginia in 1971, shortly before his 46th birthday. He was interred with military honors at Arlington National Cemetery, where his grave is one of the most visited.

🔗 Neuroscience 🔗 Physiology

The gunslinger effect, also sometimes called Bohr's law or the gunfighter's dilemma, is a psychophysical theory which says that an intentional or willed movement is slower than an automatic or reaction movement. The concept is named after physicist Niels Bohr, who first deduced that the person who draws second in a gunfight will actually win the shoot-out.

🔗 Canada 🔗 Packaging

A milk bag is a plastic bag that contains milk. Usually one of the corners is cut off to allow for pouring, and the bag is stored in a pitcher or jug.

A typical milk bag contains approximately 1 L (1.8 imp pt) of milk in South America, Iran, Israel, and continental European countries, while in Canada they contain 1+1⁄3 litres (2.3 imp pt), and in India, 0.5 L (0.9 imp pt).

In the Baltic rim countries, e.g., Estonia, and some Eastern European countries, the similar bags may also be seen used for packaging yogurt or kefir.