Archive for February, 2008

Walrasian auction; prices cannot open

Tuesday, February 26th, 2008

A Walrasian auction, introduced by Leon Walras, is a type of simultaneous auction where each agent calculates its demand for the good at every possible price and submits this to an auctioneer. The price is then set so that the total demand across all agents equals the total amount of the good. Thus, a Walrasian auction perfectly matches the supply and the demand.

Walras suggests that equilibrium will be achieved through a process of tatonnement or groping.


Walrasian auctioneer

The Walrasian auctioneer is the presumed auctioneer that matches supply and demand in a market of perfect competition. The auctioneer provides for the features of perfect competition: perfect information and no transaction costs. The process is called tâtonnement, or groping, relating to finding the market clearing price for all commodities and giving rise to general equilibrium.

The tâtonnement process works as follows. Prices are cried, and agents register how much of each good they would like to offer (supply) or purchase (demand). No transactions and no production take place at disequilibrium prices. Instead, prices are lowered for goods with positive prices and excess supply. Prices are raised for goods with excess demand. The question for the economist is under what conditions such a process will terminate in equilibrium in which demand equates to supply for goods with positive prices and demand does not exceed supply for goods with a price of zero. Although Walras was not able to provide a definitive answer to this question subsequent researchers, such as Arrow and Debreu, have provided proofs of existence under some conditions (of which the strongest one is the convexity of preferences). However, the Sonnenschein-Mantel-Debreu Theorem states that an equilibrium need not be unique.

A recent article by Richter and Wong contests the Arrow-Debreu proof and claims the following holds with respect to the computation of Walrasian equilibria:

  • The Arrow-Debreu conditions are not sufficient to guarantee existence of a computable equilibrium.
  • The rate of approximation towards an equilibrium (as defined by the current price set), cannot be given under any algorithm.


Selected publications


See also

  • Leon Walras
  • Walras’ law
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Degree; degree

Tuesday, February 26th, 2008

Degree, in the sense of measurement, is used to indicate:

  • Comparative degree (”good”, “better”) and superlative degree (”best”)
  • Severity of similar crimes (in some jurisdictions) — for example first degree murder
  • Intensity of a burn (from first degree to third degree)
  • Level of kinship (consanguinity)
  • Degree of inventiveness in inventions and patents

Degree may also refer to:

In science:

  • Degree (angle), a unit of angle measurement
  • Degree (temperature), a unit of temperature measurement
  • Degree (symbol), (°), a notation used in science, engineering and mathematics
  • Degree API, a measure of density in the petroleum industry
  • Degree Baumé, a couple of density scales
  • Degree Brix, a measure of sugar concentration
  • Degree of curvature, a unit of curvature measurement
  • Degrees of freedom (physics and chemistry)

In mathematics:

  • Degree (mathematics)

    • Degree of a polynomial
    • Degree of a field extension
    • Degree (graph theory)
    • Degree (continuous map)
    • Degrees of freedom (statistics)
    • Degrees of freedom (engineering)

In education:

  • Academic degree, an academic award or title requiring a longer study period than a diploma

    • Foundation degree
    • Associate’s degree
    • Bachelor’s degree
    • Master’s degree
    • Doctorate degree
    • Engineer’s degree
    • Specialist degree
    • Ad eundem degree
    • Honorary degree
    • Lambeth degree
    • External degree

Degree may also refer to:

  • Degree (music), a particular note of a scale in relation to the tonic
  • Degree (deodorant), a brand of antiperspirant
  • Degree (deejay), a Jamaican deejay, formerly known as General Degree
  • Degree (project), Dissemination and Exploitation of GRids in Earth science
  • A degree of initiation, often used in secret societies and some pagan religious groups

50 Divisions; are future-regarding and thus

Tuesday, February 26th, 2008

50 Divisions refers to the 50 divisions of construction information, as defined by the Construction Specifications Institute (CSI)’s MasterFormat. Before 2004, MasterFormat consisted of 16 Divisions. The standard is the most widely used standard for organizing specifications and other written information for commercial and institutional building projects in the U.S. and Canada. It provides a master list of divisions, and section numbers and titles within each division, to follow in organizing information about a facility’s construction requirements and associated activities. Standardizing the presentation of such information improves communication among all parties involved in construction projects.

MasterFormat 2004 Edition Divisions are:

PROCUREMENT AND CONTRACTING REQUIREMENTS GROUP:

  • Division 00 — Procurement and Contracting Requirements

SPECIFICATIONS GROUP

General Requirements Subgroup

  • Division 01 — General Requirements

Facility Construction Subgroup

  • Division 02 — Existing Conditions
  • Division 03 — Concrete
  • Division 04 — Masonry
  • Division 05 — Metals
  • Division 06 — Wood, Plastics, and Composites
  • Division 07 — Thermal and Moisture Protection
  • Division 08 — Openings
  • Division 09 — Finishes
  • Division 10 — Specialties
  • Division 11 — Equipment
  • Division 12 — Furnishings
  • Division 13 — Special Construction
  • Division 14 — Conveying Equipment
  • Division 15 — RESERVED FOR FUTURE EXPANSION
  • Division 16 — RESERVED FOR FUTURE EXPANSION

Facility Services Subgroup:

  • Division 20 — RESERVED FOR FUTURE EXPANSION
  • Division 21 — Fire Suppression
  • Division 22 — Plumbing
  • Division 23 — Heating Ventilating and Air Conditioning
  • Division 24 — RESERVED FOR FUTURE EXPANSION
  • Division 25 — Integrated Automation
  • Division 26 — Electrical
  • Division 27 — Communications
  • Division 28 — Electronic Safety and Security
  • Division 29 — RESERVED FOR FUTURE EXPANSION

Site and Infrastructure Subgroup:

  • Division 30 — RESERVED FOR FUTURE EXPANSION
  • Division 31 — Earthwork
  • Division 32 — Exterior Improvements
  • Division 33 — Utilities
  • Division 34 — Transportation
  • Division 35 — Waterways and Marine Construction
  • Division 36 — RESERVED FOR FUTURE EXPANSION
  • Division 37 — RESERVED FOR FUTURE EXPANSION
  • Division 38 — RESERVED FOR FUTURE EXPANSION
  • Division 39 — RESERVED FOR FUTURE EXPANSION

Process Equipment Subgroup:

  • Division 40 — Process Integration
  • Division 41 — Material Processing and Handling Equipment
  • Division 42 — Process Heating, Cooling, and Drying Equipment
  • Division 43 — Process Gas and Liquid Handling, Purification and Storage Equipment
  • Division 44 — Pollution Control Equipment
  • Division 45 — Industry-Specific Manufacturing Equipment
  • Division 46 — RESERVED FOR FUTURE EXPANSION
  • Division 47 — RESERVED FOR FUTURE EXPANSION
  • Division 48 — Electrical Power Generation
  • Division 49 — RESERVED FOR FUTURE EXPANSION

Verendrye Electric Cooperative; of ‘expectation utility’

Monday, February 25th, 2008

Verendrye Electric Cooperative is a public utility cooperative based in Velva, North Dakota. It serves as the electric distribution utility in a portion of north central North Dakota. Verendrye Electric receives power from the Central Power Electric Cooperative - in fact, Verendrye took the lead in establishing Central Power in 1949 after having to deal with a 30% rate hike from its previous power supplier in 1948.

It is named after the French Canadian explorer La Vérendrye; in its early years it was headquartered in the small town of Verendrye (northwest of Karlsruhe; now a ghost town).


External links

  • Verendrye Electric Cooperative site

Klipper; utility being identical

Monday, February 25th, 2008

Klipper is a clipboard utility for the KDE interface. It allows users of Unix-like operating systems running the KDE desktop environment to access a history of X Selections, any item of which can be reselected for pasting.


Similar Software

  • Glipper
  • Clipman
  • Desktop Data Manager


See also

  • X Window selection

Range (biology); introduced

Monday, February 25th, 2008

In biology, the range or distribution of a species is the geographical area within which that species can be found.

The term is often qualified:

  • sometimes a distinction is made between a species’ native range and the places to which it has been introduced by human agency (deliberately or accidentally), as well as where it has been re-introduced following extirpation.
  • for species which are found in different regions at different times of year, terms such as summer range and winter range are often employed.
  • for species where only part of their range is used for breeding activity, the terms breeding range and non-breeding range are used.
  • when discussing mobile animals, the species’ natural range is often discussed, as opposed to areas where it occurs as a vagrant.
  • geographic or temporal qualifiers are often added e.g. British range or pre-1950 range.

Contents


See also

  • Colonisation


Bibliography


References


External links

Burundi at the 1996 Summer Olympics; qualification introduced by

Monday, February 25th, 2008

Burundi competed in the Olympic Games for the first time at the 1996 Summer Olympics in Atlanta, United States. The nation won its first Olympic gold medal in this debut appearance at the Games.

Contents


Medals


Gold

  • Venuste Niyongabo — Athletics, Men’s 5.000 metres


Results by event


Athletics

Men’s 5.000 metres

  • Venuste Niyongabo
  • Qualification — 13:54.53
  • Semifinal — 14:03.48
  • Final — 13:07.96 (→ Gold Medal)
  • Aloys Nizigama
  • Qualification — did not start (→ did not advance)

Men’s Marathon

  • Tharcisse Gashaka — 2:32.55 (→ 90th place)

Women’s 10.000 metres

  • Qualification — 35:58.51 (→ did not advance)


References

  • Official Olympic Reports
  • International Olympic Committee results database

Implicit cost; profit

Monday, February 25th, 2008

In economics, an implicit cost occurs when one foregoes an alternative action but does not make an actual payment. (For instance, the explicit cost of a night at the movies includes the moviegoer’s ticket and soda, but the implicit cost includes the pay she would have earned if she had chosen to work instead.) Implicit costs are related to forgone benefits of any single transaction.


Examples of implicit costs

  • A firm’s use of its own capital. This is considered an implicit cost because the capital could have been rented to another firm instead. This rental income foregone, or the implicit rental rate of capital, is the firm’s opportunity cost of using its own capital. This implicit rental rate can be broken down beyond interest forgone.
  • A firm’s use of its owner’s time and/or financial resources.
  • Economic depreciation.


Implicit cost and economic profit

Economic profit equals total revenues minus both implicit and explicit costs. In contrast, accounting profit equals total revenues minus explicit costs. Since economic profit includes opportunity costs, it will always be less than or equal to accounting profit.


See

also

  • Explicit cost
  • Economic profit
  • Opportunity cost

KPU; utilities allow

Monday, February 25th, 2008

KPU is an abbreviation that can mean:

  • Kripke–Platek set theory with urelements, an axiom system for set theory
  • Kenya People’s Union
  • Korea Polytechic University one of universities in Siheung, Gyeonggi-do, South Korea
  • Ketchikan Public Utilities Electric, Water and Telephone for the City and Borough of Ketchikan, South East Alaska.

Retirement annuity plan; income

Monday, February 25th, 2008

A Retirement Annuity Plan (RAP) is a UK pension plan designed to build a lump sum for retirement. Part of the lump sum must be used to buy an annuity and part can be taken a tax free lump sum.

The plans were introduced under section 226 of the Income and Corporation Taxes Act 1970 and are often referred to as section 226 contracts. However they are currently legislated under section 620 of the Income and Corporation Taxes Act 1988 and are therefore also known as section 620 contracts.


Tax treatment

Contributions receive basic tax relief claimed at source (although this was only introduced in 2001). The income and gains in the plan are free from tax (with the exception of the non-reclaimable 10% tax credit). At maturity the tax free cash can be taken. The tax free cash lump sum is calculated with reference to the initial annual income. The formula is often described as: the tax free cash is equal to three times the resiudual income.

This tax regime is being abolished under pension simplification introduced on A-day.


See also

  • Pensions
  • UK Pension Provision
  • Personal pension schemes
  • Stakeholder pension schemes
  • Pension simplification

Gyeyul; derives

Monday, February 25th, 2008

Gyeyul is the Korean name applied to a branch of Buddhism that specializes in the study of monastic discipline, or Vinaya. The Gyeyul school derives from the Chinese or Vinaya school.


See also

  • Sangha
  • List of Korea-related topics

Actions per minute; not be mistaken for

Monday, February 25th, 2008

Actions Per Minute, commonly abbreviated as APM, is a term used mostly in real time strategy games. APM is commonly mistaken as AMP.

Contents


Actions per Minute

Actions per minute is the number of actions completed within a minute of gameplay in a real time strategy game. High APM is usually associated with skill, because it indicates both that the player has the mental alertness and knowledge of the game to form a complex strategy, and that the player has the manual dexterity to execute that strategy at high speed. A high APM is also an indicator that the player has good “micro” skills. Software has been developed to analyze players’ APM in these games.BWChart FAQ


Speed in APM

Speed is one factor determining a player’s APM. It measures the rapidity at executing actions during gameplay. This includes the number of keystrokes and mouse clicks the player performs. The higher the speed rate, the higher the APM will be. Many players mistaken speed as to determining a player’s APM. Players will sometimes stroke two keys close together continually, or ‘trill’, at times of relative inactivity to increase the APM. This is usually employed so that the player displays a higher level of skill than they actually do. Sometimes though, players claim that this type of action is just a nervous reaction or a habit.


Efficiency in APM

Efficiency is another factor determining a player’s APM. Efficiency simply means how well a player can productively execute desired actions without wasting necessary time to execute other actions. This shows the valid APM during gameplay and does not include spammed actions. Any spammed actions during a gameplay will attribute to an increase of speed. Valid APM is generally measured and calculated by only the efficiency and accuracy of a player’s gameplay.


Accuracy in APM

Accuracy is the third and final factor determining a player’s APM. Accuracy is the coordination of precise mouse clicks and keystrokes. Greater accuracy will result in fewer mis-clicks and mis-strokes; thus the player’s efficiency increases resulting in a more accurate valid APM. Players who have greater accuracy can perform other vital tasks during gameplay and can multitask between two or more other actions without losing efficiency.


References

Abiodun; favored by those

Monday, February 25th, 2008

Abiodun (reigned c. 1770–1789) was an eighteenth-century alaafin, or ruler of the Oyo people in what is now Nigeria. Coming to the throne shortly after the Oyo subjugation of neighboring Dahomey, Abiodun soon found himself embroiled in a civil war over the goals of the newly wealthy state.
Bashorun Gaha had used his power to pervert the constitutional terms of abdication in a bid to limit the powers of the Alaafin and gain more political power for himself. During Gaha’s power play, he had succeeded in removing three kings before Abiodun curtailed his excesses and had him burned.
In terms of trade, while Abiodun favored economic expansion for its own sake, his opponents favored using the wealth from Dahomey’s tribute to finance further military expansion. Abiodun soon proved victorious and pursued a policy of peaceful trade with the European merchants of the coast. This course significantly weakened the army, leaving his successor, Awole, facing a number of local revolts.

Abiodun’s reign is generally remembered as a time of peace and prosperity for the Oyo, though Nigerian playwright Femi Òsófisan portrays him as a despot in his play The Chattering and the Song (1973).


External links

  • Oyo empire
  • The dictating currents and the questioning of tyranny in Africa: an intertextual study of Fémi Osófisan’s Yungba-Yungba and the dance contest

Norway at the 1976 Summer Olympics; qualification introduced by

Monday, February 25th, 2008

Norway was represented at the 1976 Summer Olympics in Montreal by the Norwegian Olympic Committee and Confederation of Sports.

Contents


Medals

Norway finished in 21st position in the final medal rankings, with one gold medal and one silver medal.


Gold

  • Alf Hansen and Frank Hansen — Rowing, Men’s Double Sculls


Silver

  • Finn Tveter, Rolf Andreassen, Arne Bergodd, and Ole Nafstad — Rowing, Men’s Coxless Fours


Results by event


Archery

In the second appearance by the nation in the archery competition at the Olympics, Norway was represented by only one man. A veteran of the 1972 Summer Olympics, Jan Erik Humlekjær shot two points less than his performance of four years before. Nevertheless, he moved up eight places in the ranking.

Men’s Individual Competition:

  • Jan Erik Humlekjær — 2337 points (→ 24th place)


Athletics

Men’s 1500 metres

  • Lars Martin Kaupang
  • Heat — 3:44.59 min (→ did not advance)

Women’s 1500 metres

  • Grete Waitz
  • Heat — 4:07.20 min (→ advanced to the semi final)
  • Semi final — 4:04.80 min (→ did not advance)

Men’s 5000 metres

  • Knut Kvalheim
  • Heat — 13:20.60 min (→ advanced to the final)
  • Final — 13:30.33 min (→ 9th place)

Men’s 10.000 metres

  • Knut Børø
  • Heat — 28:23.07 min (→ advanced to the final)
  • Final — did not finish (→ no ranking)

Men’s High Jump

  • Terje Totland
  • Qualification — 2.16 m (→ advanced to the final)
  • Final — 2.18m (→ 9th place)
  • Leif Roar Falkum
  • Qualification — 2.16 m (→ advanced to the final)
  • Final — 2.10m (→ 14th place)

Women’s High Jump

  • Astrid Tveit
  • Qualification — 1.70 m (→ did not advance)

Men’s Discus Throw

  • Knut Hjeltnes
  • Qualification — 61.30 m (→ advanced to the final)
  • Final — 63.06 m (→ 7th place)

Men’s Javelin Throw

  • Terje Thorslund
  • Qualification — 82.52 m (→ advanced to the final)
  • Final — 78.24 m (→ 11th place)
  • Bjørn Grimnes
  • Qualification — 80.32 m (→ advanced to the final)
  • Final — 74.88 m (→ 14th place)


Cycling

Men’s Individual Road Race

  • Thorleif Andresen — 4:49:01 (→ 38th place)
  • Geir Digerud — 5:04:42 (→ 55th place)
  • Pål Henning Hansen — did not finish (→ no ranking)
  • Stein Bråthen — did not finish (→ no ranking)

Men’s 1.000m Time Trial

  • Harald Bundli — 1:08.093 (→ 7th place)

Men’s 4.000m Individual Pursuit

  • Jan Georg Iversen — 7th place

Canonical coordinates; bundle

Monday, February 25th, 2008

In mathematics and classical mechanics, canonical coordinates are a particular set of coordinates on the phase space, or equivalently, on the cotangent manifold of a manifold. Canonical coordinates arise naturally in physics in the study of Hamiltonian mechanics. As Hamiltonian mechanics is generalized by symplectic geometry and canonical transformations are generalized by contact transformations, so the 19th century definition of canonical coordinates in classical mechanics may be generalized to a more abstract 20th century definition in terms of cotangent bundles.

This article defines the canonical coordinates as they appear in classical mechanics. A closely related concept also appears in quantum mechanics; see the Stone-von Neumann theorem and canonical commutation relations for details.

Contents


Definition, in classical mechanics

In classical mechanics, canonical coordinates are the coordinates <math>q_i\,</math> and <math>p_i\,</math> in phase space that are used in the Hamiltonian formalism. The canonical coordinates satisfy the fundamental Poisson bracket relations:

<math>\{q_i, q_j\} = 0 \qquad \{p_i, p_j\} = 0 \qquad \{q_i, p_j\} = \delta_{ij}</math>

Canonical coordinates can be obtained from the generalized coordinates of the Lagrangian formalism by a Legendre transformation, or from another set of canonical coordinates by a canonical transformation.


Definition, on cotangent bundles

Canonical coordinates are defined as a special set of coordinates on the cotangent bundle of a manifold. They are usually written as a set of <math>(q^i,p_j)</math> or <math>(x^i,p_j)</math> with the x ’s or q ’s denoting the coordinates on the underlying manifold and the p ’s denoting the conjugate momentum, which are 1-forms in the cotangent bundle at point q in the manifold.

A common definition of canonical coordinates is any set of coordinates on the cotangent bundle that allow the canonical one form to be written in the form

<math>\sum_i p_i\,\mathrm{d}q^i</math>

up to a total differential. A change of coordinates that preserves this form is a canonical transformation; these are a special case of a symplectomorphism, which are essentially a change of coordinates on a symplectic manifold.

In the following exposition, we assume that the manifolds are real manifolds, so that cotangent vectors acting on tangent vectors produce real numbers.


Formal development

Given a manifold Q, a vector field X on Q (or equivalently, a section of the tangent bundle TQ) can be thought of as a function acting on the cotangent bundle, by the duality between the tangent and cotangent spaces. That is, define a function

<math>P_X:T^*Q\to \mathbb{R}</math>

such that

<math>P_X(q,p)=p(X_q)</math>

holds for all cotangent vectors p in <math>T_q^*Q</math>. Here, <math>X_q</math> is a vector in <math>T_qQ</math>, the tangent space to the manifold Q at point q. The function <math>P_X</math> is called the momentum function corresponding to X.

In local coordinates, the vector field X at point q may be written as

<math>X_q=\sum_i X^i(q) \frac{\partial}{\partial q^i}</math>

where the <math>\partial /\partial q^i</math> are the coordinate frame on TQ. The conjugate momentum then has the expression

<math>P_X(q,p)=\sum_i X^i(q) \;p_i</math>

where the <math>p_i</math> are defined as the momentum functions corresponding to the vectors <math>\partial /\partial q^i</math>:

<math>p_i = P_{\partial /\partial q^i}</math>

The <math>q^i</math> together with the <math>p_j</math> together form a coordinate system on the cotangent bundle <math>T^*Q</math>; these coordinates are called the canonical coordinates.


Generalized coordinates

In Lagrangian mechanics, a different set of coordinates are used, called the generalized coordinates. These are commonly denoted as <math>(q^i,\dot{q}^i)</math> with <math>q^i</math> called the generalized position and <math>\dot{q}^i</math> the generalized velocity. When a Hamiltonian is defined on the cotangent bundle, then the generalized coordinates are related to the canonical coordinates by means of the Hamilton–Jacobi equations.


See also

  • symplectic manifold
  • symplectic vector field
  • symplectomorphism

Gross Output; consumption

Monday, February 25th, 2008

Gross Output is an economic concept used in national accounts such as the United Nations System of National Accounts (UNSNA) and the US National Income and Product Accounts (NIPA). It is equal to the value of net output or GDP (also known as gross value added) plus intermediate consumption.

Gross Output represents, roughly speaking, the total value of sales by producing enterprises in an accounting period (e.g. a quarter or a year), before subtracting the value of intermediate goods used up in production. This description is not quite accurate though, among other things because flows relating to government services and households are also included.

To obtain a measure of gross value added or Net output, the value of intermediate goods and services must be subtracted from Gross Output. Net value added is obtained by additionally subtracting consumption of fixed capital (depreciation).

The statistical definition of Gross Output is dependent upon the definition of production applied. Typically some economic flows and activities are excluded from coverage in calculating the value of Gross Output, on the ground that they are unrelated to production in the domestic economy. These include foreign transactions, property income, transfers, and various government disbursements, unpaid housework and voluntary work. On the other hand, items are included which some economists would regard as spurious, such as the imputed rental value of owner-occupied housing (this is the average rents, at market rates, which owners of residential housing would receive if they rented out the housing they occupy).


See also

  • GDP
  • Intermediate consumption
  • Net output
  • United Nations System of National Accounts (UNSNA)
  • National accounts

Sometimes a Great Notion; interest. The notion

Monday, February 25th, 2008

Sometimes

a Great Notion may refer to:

  • Sometimes a Great Notion (novel)
  • Sometimes a Great Notion (1971 film)

NCST; computing

Monday, February 25th, 2008

NCST can refer to:

  • National Centre for Software Technology in India, now Centre for Development of Advanced Computing (C-DAC)
  • National College of Science and Technology in Philippines.
  • North Carolina State University in United States

Konrad Adenauer (aircraft); is analogous to

Sunday, February 24th, 2008

The Konrad Adenauer is a German aircraft used by the head-of-government for official travel and diplomatic business.


References

  • Nuclear Dispute with Iran: Merkel Pushes Russian Diplomatic Role, by Ralf Beste, Ralf Neukirch and Gabor Steingart, from Der Spiegel, January 23, 2006


See also

  • Air Force One, the analogous plane used by the United States President.

Cardinal utility; its utility

Sunday, February 24th, 2008

In economics, cardinal utility is a theory of utility under which the utility (roughly, satisfaction) gained from a particular good or service can be measured and that the magnitude of the measurement is meaningful. Under cardinal utility theory, the util is a unit of measurement much like the metre or second. A util has a fixed size, making comparisons based on ratios of utils possible. Perhaps more importantly, however, cardinal utility allows for comparisons of utility across persons—if a particular good gives Alice 200 utils but Bob only gets 100 utils from the same good, the good is said to give Alice twice as much utility as it does Bob.

This sort of comparison is of great theoretical value in social planning and ethics. Under the framework of utilitarianism, actions (including production of goods and provision of services) are judged by their contributions to overall happiness. Cardinal utility provides a way of judging the “greatest good to the greatest number”. An act that reduces one person’s utility by 75 utils while increasing two others’ by 50 utils each has increased overall utility by 25 utils and is thus a positive contribution; one that costs the first person 125 utils while giving the same 50 each to two other people has resulted in a net loss of 25 utils.

This ability to neatly compare utilities in theory runs into problems in practice. There are major difficulties in measuring utility, which is inherently subjective. Unlike with distance or time, one cannot simply use a ruler or stopwatch to measure satisfaction. It is not simple to definitively say whether a good is worth 50, 75, or 125 utils to a person, or even if it is worth the same number of utils to two different people. These problems have resulted in a shift in microeconomic theory towards ranked preferences or ordinal utility, in which a good with a higher utility is preferred to one with lower utility but the magnitude of the difference has no meaning.

There remain economists who believe that utility can be measured. These measures are not perfect but can act as a proxy for the utility. Lancaster’s characteristics approach to consumer demand illustrates this point.

Community of interest; immediate interest. The

Sunday, February 24th, 2008

A Community of interest is a community of people who share a common interest or passion, such as rugby fans on Rugby365.com, or music lovers on MP3.com. These people exchange ideas and thoughts about the given passion, but may know (or care) little about each other outside of this area. Participation in a community of interest can be compelling, entertaining and create a ‘sticky’ community where people return frequently and remain for extended periods. They sometimes cannot be easily defined by a particular geographical area.


Related to

  • Communities of Action
  • Communities of Circumstance
  • Communities of Position
  • Communities of Practice
  • Communities of Purpose
  • Community of inquiry


See also

  • Sense of community


External links

  • External and shareable artifacts as opportunities for social creativity in communities of interest
  • Communities of Interest: Learning through the Interaction of Multiple Knowledge Systems
  • Bradford (UK) Communities of Interest site Deals with Communities of Interest within Bradford.

Prime decomposition (3-manifold); same bundle;

Sunday, February 24th, 2008

In mathematics, the prime decomposition theorem for 3-manifolds states that every compact, orientable 3-manifold is the connected sum of a unique (up to homeomorphism) collection of prime 3-manifolds.

The manifold is prime if it can not be presented as a connected sum in a non-trivial way, where the trivial way is

<math>P=P\#S^3.</math>

If <math>P</math> is a prime 3-manifold then either it is
<math>S^2\times S^1</math> or the non-orientable <math>S^2</math> bundle over <math>S^1</math>,
or any embedded 2-sphere in <math>P</math> bounds a ball, i.e. is irreducible. So the theorem can be restated to say that there is a unique connected sum decomposition into irreducible 3-manifolds and <math>S^2 \times S^1</math>’s.

The prime decomposition holds also for non-orientable 3-manifolds, but the uniqueness statement must be modified slightly: every compact, non-orientable 3-manifold is a connected sum of irreducible 3-manifolds and non-orientable <math>S^2</math> bundles over <math>S^1</math>. This sum is unique as long as we specify that each summand is either irreducible or a non-orientable <math>S^2</math> bundle over <math>S^1</math>.

The proof is based on normal surface techniques originated by Hellmuth Kneser. Existence was proven by Kneser, but the exact formulation and proof of the uniqueness was done more than 30 years later by John Milnor.

Oldfieldia; Bentham

Sunday, February 24th, 2008

Oldfieldia is a plant genus under the family Picrodendraceae, the only of its subtribe (Paiveusinae).

The genus includes Cecchia Chiov. and Paivaeusa Welw..

South Central Arkansas Electric Cooperative; utility;

Sunday, February 24th, 2008

South Central Arkansas Electric Cooperative is a non-profit rural electric utility cooperative headquartered in Arkadelphia, Arkansas. The Cooperative was organized in 1940.

The Cooperative serves portions of eight counties in the state of Arkansas, in a territory generally west and southwest of Arkadelphia.

As of September 2005, the Cooperative had more than 1,770 miles of distribution lines, 9 substations and services 7,300 member accounts.


External links

  • South Central Arkansas Electric Cooperative

Leased access; in prices

Sunday, February 24th, 2008

Leased Access airtime is airtime that the Federal Communications Commission mandates must be provided by cable operators (i.e. companies like Comcast and Time Warner Cable) for use by cable programmers, i.e., those who make cable programming, who are not owned by the operators. The prices for leased access airtime are subject to a maximum set by an FCC formula and therefore in theory cannot be manipulated by cable companies. Cable companies, however, can “manipulate” prices through lobbying the FCC. Indeed, in 1997, the FCC set maximum prices based on an “average implicit fee” formula which set the prices considered by cable programmers to be very high. Lower prices would likely encourage increased usage of leased access by independent programmers. Leased access airtime may be purchased by individuals or groups with E&O insurance for the purposes of airing television content, usually locally produced.

1733; their preferences

Sunday, February 24th, 2008

Year 1733 (MDCCXXXIII) was a common year starting on Thursday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Monday of the 11-day slower Julian calendar).

Contents


Events of


January - June

  • February 12 - British colonist James Oglethorpe founds Savannah, Georgia.
  • April - Royal Colony of North Carolina Commissioners John Watson, Joshua Grainger, Michael Higgins and James Wimble plan the town of New Carthage (which would eventually become Wilmington, North Carolina on the east side of the Cape Fear River).
  • May 29 - Right of Canadians to keep Indian slaves upheld at Quebec.


July - December

  • July 30 - First Freemasons lodge opened in what will become the United States of America.


Births

  • March 13 - Joseph Priestley, English scientist and minister (died 1804)
  • May 4 - Jean-Charles de Borda, French mathematician, physicist, political scientist, and sailor (died 1799)
  • July 27 - Jeremiah Dixon, English surveyor and astronomer (died 1779)
  • September 18 - George Read, American lawyer and signer of the Declaration of Independence (died 1798)
  • October 14 - François Sebastien Charles Joseph de Croix, Count of Clerfayt, Austrian field marshal (died 1798)
  • November 16 - Siraj ud-Daulah, the last independent ruler of Bengal of undivided India (died 1757)
See also .


Deaths

  • January 25 - Gilbert Heathcote, Mayor of London (born 1652)
  • February 1 - King August II of Poland (born 1670)
  • March 4 - Claude de Forbin, French naval commander (born 1656)
  • April 19 - Elizabeth Villiers, mistress of William III of England (born 1657)
  • May 10 - Barton Booth, English actor (born 1681)
  • May 18 - Georg Böhm, German organist (born 1661)
  • August 16 - Matthew Tindal, English deist (born 1657)
  • June 23 - Johann Jakob Scheuchzer, Swiss scholar (born 1672)
  • September 12 - François Couperin, French composer (born 1668)
  • October 25 - Giovanni Gerolamo Saccheri, Italian mathematician (born 1667)
  • October 31 - Eberhard Ludwig, Duke of Württemberg, (born 1676)
See also .

Marginal concepts; utility

Sunday, February 24th, 2008

In economics, marginal concepts refer to the effect of producing or consuming one more of a good, i.e. at the edge, or margin, of the total produced/consumed.

For example, marginal cost refers to the cost of producing one more unit of some good. In general this will be lower than the average cost because the average cost includes fixed costs. (See economies of scale). Marginal benefit is the extra utility accrued from one additional unit of a good.

Similarly marginal utility is the additional utility (satisfaction or benefit) that a consumer derives from an additional unit of a commodity or service. It is assumed that marginal utility generally falls as consumption increases, so that one’s 10th doughnut in a day is less satisfying than the first or second.

Other marginal concepts include:

  • marginal tax rate
  • marginal propensity to save and consume
  • marginal rate of substitution

The related concept of elasticity is the ratio of the incremental percentage change in one variable with respect to an incremental percentage change in another variable.

Expenditure minimization problem; consumer’s indirect utility

Sunday, February 24th, 2008

In microeconomics, the expenditure minimization problem is the dual problem to the utility maximization problem: “how much money do I need to be happy?”. This question comes in two parts. Given a consumer’s utility function, prices, and a utility target,

  • how much money would the consumer need? This is answered by the expenditure function.
  • what could the consumer buy to meet this utility target while minimizing expenditure? This is answered by the Hicksian demand correspondence.

Contents


Expenditure function

Formally, the expenditure function is defined as follows. Suppose the consumer has a utility function <math>u</math> defined on <math>L</math> commodities. Then the consumer’s expenditure function gives the amount of money required to buy a package of commodities at given prices <math>p</math> that give utility greater than <math>u^*</math>,

<math>e(p, u^*) = \min_{x \in \geq{u^*}} p \cdot x</math>

where

<math>\geq{u^*} = \{x \in \textbf R^L_+ : u(x) \geq u^*\}</math>

is the set of all packages that give utility at least as good as <math>u^*</math>.


Hicksian demand correspondence

Secondly, the Hicksian demand correspondence <math>h(p, u^*)</math> is defined as the cheapest package that gives the desired utility. It can be defined in terms of the expenditure function with the Marshallian demand correspondence