wiktionarypar constraintConstraint is the element factor or a subsystem that works as a bottleneck. It restricts an entity, project, or system such as a manufacturing or decision making process from achieving its potential or higher level of output with reference to its goal. Constraint may refer to Theory of Constraints , in business management Loading gauge or structure gauge constraints in engineering A constraint on constrained writing , in literature For example, Oulipo Constraints Oulipian constraints In mathematics Constraint mathematics Constraint information theory Constraint algorithm such as SHAKE, or LINCS In computing Constraint satisfaction , in computer science Constraint logic programming Finite domains Finite domain constraints , in constraint satisfaction. Integrity constraints , an element of database design See also Carrier s constraint Restraint disambiguation disambig es Restricci n ... more details
In artificial intelligence and operations research , a regular constraint is a kind of global constraint . It can be used to solve a particular type of puzzle called a nonogram or logigrams. External links Paltzer, Nikos. http www.ps.uni sb.de courses seminar ws04 papers paltzer.pdf Regular Language Membership Constraint Category Constraint programming Compu AI stub Mathapplied stub ... more details
for a graph in electronic design automation Constraint graph layout In constraint satisfaction research of artificial intelligence and operations research , constraint graphs and hypergraphs are used to represent relations among constraints in a constraint satisfaction problem . Constraint hypergraph The constraint hypergraph of a constraint satisfaction problem is a hypergraph in which hypervertices correspond to the variables and the hyperedges correspond to the constraints. Two hypervertices are in the same hyperedge if the two variables occur in the same constraint. ref name handbook Primal constraint graph The primal constraint graph or simply primal graph also the Gaifman graph of a constraint satisfaction problem is the graph mathematics graph whose nodes are the variables of the problem and an edge joins a pair of variables if the two variables occur together in a constraint. ref name handbook Handbook of Constraint Programming , by Francesca Rossi, Peter Van Beek, Toby Walsh 2006 ISBN 0444527265, http books.google.com books?id Kjap9ZWcKOoC&pg PA212&dq 22primal constraint graph 22 wikipedia&ei XnTzSP OCoPytQO1zpD2Bg&sig ACfU3U029fE32OVFYg63vL PZ4bFsvgBYQ PPA212,M1 p. 211, 212 ref The primal constraint graph is in fact the primal graph hypergraphs primal graph of the constraint hypergraph. Dual constraint graph The set of variables involved in a constraint is called the constraint scope . The dual constraint graph is the graph in which the vertices are all possible constraint scopes involved in the constraints of the problem and two vertices are connected by an edge if the corresponding scopes have common variables. ref name handbook References reflist Category Constraint programming Category Application specific graphs math stub ... more details
In constraint satisfaction , constraint inference is a relationship between constraints and their consequences. A set of constraints math D math entails a constraint math C math if every solution to math D math is also a solution to math C math . In other words, if math V math is a valuation of the variables in the scopes of the constraints in math D math and all constraints in math D math are satisfied by math V math , then math V math also satisfies the constraint math C math . Some operations on constraints produce a new constraint that is a consequence of them. Constraint composition operates on a pair of binary constraints math x,y ,R math and math y,z ,S math with a common variable. The composition of such two constraints is the constraint math x,z ,Q math that is satisfied by every evaluation of the two non shared variables for which there exists a value of the shared variable math ... x,y ,R math and math y,z ,S math . Constraint projection restricts the effects of a constraint to some of its variables. Given a constraint math t,R math its projection to a subset math t math of its variables is the constraint math t ,R math that is satisfied by an evaluation if this evaluation can be extended to the other variables in such a way the original constraint math t,R math is satisfied ... of possibly non binary constraints the generated constraint is on an arbitrary subset of the variables ..., the extended composition of them is the constraint math A,R math where an evaluation of math A math satisfies this constraint if it can be extended to the other variables so that math C 1, ldots,C m math are all satisfied. See also Constraint satisfaction problem References cite book first Rina last Dechter title Constraint processing publisher Morgan Kaufmann year 2003 url http ... Principles of constraint programming publisher Cambridge University Press year 2003 ISBN 0 521 82583 ... year 1998 publisher MIT Press ISBN 0 262 13341 5 Category Constraint programming Category ... more details
Original research date June 2011 Programming paradigms Constraint programming is a programming paradigm wherein relations between variables are stated in the form of constraint mathematics constraint s. Constraints .... This makes constraint programming a form of declarative programming . The constraints used in constraint programming are of various kinds those used in constraint satisfaction problem s e.g. A or B ... are usually embedded within a programming language or provided via separate software libraries. Constraint programming began with constraint logic programming , which embeds constraints into a logic ... class of constraints that were introduced in Prolog II . The first implementations of constraint ... . Mostly, constraints are implemented in imperative languages via constraint solving toolkits , which are separate libraries for an existing imperative language. Constraint logic programming main Constraint logic programming Constraint programming is an embedding of constraints in a host language ... constraint logic programming . The two paradigms share many important features, like logical variables and backtracking . Today most Prolog implementations include one or more libraries for constraint ... some are more natural to write as constraint programs. The constraint programming approach is to search .... A problem is typically stated as a state of the world containing a number of unknown variables. The constraint program searches for values for all the variables. Temporal concurrent constraint programming TCC and non deterministic temporal concurrent constraint programming NTCC are variants of constraint programming that can deal with time. Some popular constraint logic languages are http www.probp.com ... software free Prolog system containing several libraries for constraint solving Claire programming ... free software GPL Domains The constraints used in constraint programming are typically over some specific domains. Some popular domains for constraint programming are Boolean datatype boolean domains ... more details
In mathematics , a constraint is a condition that a solution to an optimization mathematics optimization problem must satisfy. There are two types of constraints equality constraints and inequality constraints . The set of solutions that satisfy all constraints is called the candidate solution feasible set . Example The following is a simple optimization problem math min f bold x x 1 2 x 2 4 math subject to math x 1 ge 1 math and math x 2 1, , math where math bold x math denotes the Vectorization mathematics vector x sub 1 sub , x sub 2 sub . In this example, the first line defines the function to be minimized called the objective or cost function . The second and third lines define two constraints, the first of which is an inequality constraint and the second is an equality constraint. These two constraints define the feasible set of candidate solution s. Without the constraints, the solution would be math 0,0 , math where math f bold x math has the lowest value. But this solution does not satisfy the constraints. The solution of the constrained optimization problem stated above but math bold x 1,1 math , which is the point with the smallest value of math f bold x math that satisfies the two constraints. Terminology If a constraint is an equality at a given point, the constraint is said to be visible anchor binding , as the point cannot be varied in the direction of the constraint. If a constraint is an inequality at a given point, the constraint is said to be visible anchor non binding , as the point can be varied in the direction of the constraint. If a constraint is not satisfied, the point is said to be Feasible region infeasible . See also Constraint satisfaction problem Karush&ndash Kuhn&ndash Tucker conditions Lagrange multipliers Level set Linear programming Nonlinear programming External links http www unix.mcs.anl.gov otc Guide faq nonlinear programming faq.html Nonlinear programming FAQ http glossary.computing.society.informs.org Mathematical Programming ... more details
In artificial intelligence and operations research , constraint satisfaction is the process of finding a solution to a set of Constraint mathematics constraint s that impose conditions that the Variable ... that satisfies all constraints. The techniques used in constraint satisfaction depend on the kind of constraints being considered. Often used are constraints on a finite domain, to the point that constraint ... or local search constraint satisfaction local search . Constraint propagation are other methods ... or prove it unsatisfiable, but not always. Constraint propagation methods are also used in conjunction ... or the simplex algorithm . Constraint satisfaction originated in the field of artificial intelligence ... into a programming language were developed. Languages often used for constraint programming are Prolog and C . Constraint satisfaction problem main Constraint satisfaction problem As originally ... take. Informally, a finite domain is a finite set of arbitrary elements. A constraint satisfaction ... of constraints, each constraint specifying the allowed values for a group of variables. A solution ... values of the variables that would satisfy the constraint. One of the most used constraints is the one ... be expressed as constraint satisfaction problems are the Eight queens puzzle , the Sudoku solving ... definition of a constraint satisfaction problem, arithmetic equations and inequalities bound the values ... the definition of a constraint satisfaction problem , which is limited to finite domains. They are however used often in constraint programming . Solving Constraint satisfaction problems on finite ... of backtracking , constraint propagation , and Local search optimization local search . These techniques ... been generalized to any finite CSP in another book by the same author lang en Constraint Resolution Theories ref name Constraint Resolution Theories en cite news first Denis last Berthier titre lang en Constraint Resolution Theories url http www.carva.org denis.berthier CRT work Lulu Publishers, ISBN ... more details
A check constraint also known as table check constraint is a condition that defines valid data when adding or updating an entry in a table of a relational database . A check constraint is applied to each row in the table. The constraint must be a predicate. It can refer to a single or multiple columns of the table. The result of the predicate can be either TRUE, FALSE, or UNKNOWN, depending on the presence of Null SQL NULLs . If the predicate evaluates to UNKNOWN, then the constraint is not violated and the row can be inserted or updated in the table. This is contrary to predicates in WHERE clauses in Select SQL SELECT or Update SQL UPDATE statements. For example, in a table containing products, one could add a check constraint such that the price of a product and quantity of a product is a non negative value PRICE 0 QUANTITY 0 If these constraints were not in place, it would be possible to have a negative price 30 or quantity 3 items . Check constraints are used to ensure the validity of data in a database and to provide data integrity . If they are used at the database level, applications ... invalid, even if the application itself accepts invalid data. Definition Each check constraint ... CREATE TABLE table name ..., CONSTRAINTconstraint name CHECK predicate , ... ALTER TABLE table name ADD CONSTRAINTconstraint name CHECK predicate If the check constraint refers to a single column only, it is possible to specify the constraint as part of the column definition. CREATE TABLE table name ... column name type CHECK predicate , ... NOT NULL Constraint A NOT Null SQL NULL constraint is functionally equivalent to the following check constraint with an code IS NOT NULL code predicate ... are able to optimize performance when the code NOT NULL code constraint syntax is used as opposed to the CHECK constraint syntax given above. ref PostgreSQL 8.3devel Documentation, Chapter 5. Data ... modifications to these records would then be prevented by the CHECK constraint. Some examples of dangerous ... more details
In constraint satisfaction problem constraint satisfaction backtracking algorithm s, constraint learning ... is found. This new constraint may reduce the search space , as future partial evaluations may ... assigned variable, as expected by recursion. A constraint learning algorithm differs because it tries to record some information, before backtracking, in form of a new constraint. This can reduce the further ... with this new constraint. If the algorithm has learned the new constraint, it will backtrack ... solution math x 1 a 1, ldots,x k a k math is inconsistent, the problem instance implies the constraint .... However, recording this constraint is not useful, as this partial solution will not be encountered ..., the corresponding constraint may be useful in the subsequent search, as the same subset of the partial .... If this subset is inconsistent and the algorithm has stored this fact in form of a constraint ... a solution. cellpadding 20 Image Constraint learning 1.svg Image Constraint learning 2.svg Image Constraint ... x 1 math and math x 4 math only. This fact can be stored in a new constraint. If the algorithm reaches the same values of math x 1 math and math x 4 math again, the new constraint blocks the search. Efficiency of constraint learning The efficiency of constraint learning algorithm is balanced between two factors. On one hand, the more often a recorded constraint is violated, the more often backtracking ... not the only feature of learned constraints to take into account. Indeed, a small constraint may ... again. A larger constraint whose violating values are more similar to the current partial assignment may be preferred in such cases. Various constraint learning techniques exist, differing ... of the truth evaluation of math x 1, ldots,x k math to variables that are in a constraint with math x k 1 math , provided that this constraint contains no unassigned variable. Learning ... of variables are in the same constraint, which can be found out from the graph associated to the constraint ... more details
No footnotes date April 2009 In loop quantum gravity , dynamics such as time evolutions of fields are controlled by the Hamiltonian constraint . The identity of the Hamiltonian constraint is a major open question in quantum gravity , as is extracting of physical observables from any such specific constraint. The Thomas Thiemann Thiemann Operator physics operator has been proposed as such a constraint. Although this operator defines a complete and consistent quantum theory, doubts have been raised as to the physical reality of this theory due to inconsistencies with classical general relativity the quantum constraint algebra closes, but it is not isomorphic to the classical constraint algebra of GR, which is seen as circumstantial evidence of inconsistencies definitely not a proof of inconsistencies , and so variants have been proposed. External links http relativity.livingreviews.org open?pubNo lrr 1998 1&page node27.html Overview by Carlo Rovelli http arxiv.org abs gr qc 9606088 Thiemann s paper in Physics Letters http arxiv.org pdf gr qc 9710008 Good information on LQG Category Loop quantum gravity quantum stub ... more details
Orphan date February 2009 In robot motion planning , a Pfaffian constraint is a set of k linearly independent Constraint mathematics constraint s linear in velocity, i.e., of the form math A q dot q 0 math One source of Pfaffian constraints is rolling without slipping in wheeled robot s. ref name Choset2005 cite book author Choset, H.M. year 2005 title Principles of Robot Motion Theory, Algorithms, and Implementation publisher The MIT Press isbn 0262033275 ref References reflist Category Robot kinematics Category Control theory ... more details
Unreferenced date January 2008 dicdef Binary constraint , in mathematical optimization , is a constraint that involves exactly two variables. For example, consider the n queens problem , where the goal is to place n Queen chess chess queens on an n by n chessboard such that none of the queens can attack each other horizontally, vertically, or diagonally . The formal set of constraints are therefore Queen 1 can t attack Queen 2 , Queen 1 can t attack Queen 3 , and so on between all pairs of queens. Each constraint in this problem is binary, in that it only considers the placement of two individual queens. Long comment to avoid being listed on short pages Category Mathematical optimization Category Constraint programming Mathapplied stub ... more details
Orphan date October 2008 A transition constraint is a way of enforcing that the data doesn t enter an impossible state because of a previous state. For example, it shouldn t be possible for a person to change from being married to being single, never married . The only valid states after married might be divorced , widowed , or deceased . Transition constraint is commonly used in database model s such as relational databases . References http citeseer.ist.psu.edu 612731.html Modelling Transition Constraints ResearchIndex Category Data modeling database stub ... more details
Orphan date February 2009 Unreferenced date February 2007 In theoretical physics , a constraint algebra is a linear space of all Constraint mathematics constraint s and all of their polynomial functions or functionals whose action on the physical vectors of the Hilbert space should be equal to zero. For example, in electromagnetism, the equation for the Gauss law math nabla cdot vec E rho math is an equation of motion that does not include any time derivatives. This is why it is counted as a constraint, not a dynamical equation of motion. In quantum electrodynamics , one first constructs a Hilbert space in which Gauss law does not hold automatically. The true Hilbert space of physical states is constructed as a subspace of the original Hilbert space of vectors that satisfy math nabla cdot vec E x rho x psi rangle 0. math In more general theories, the constraint algebra may be a noncommutative algebra . See also First class constraints Category Quantum mechanics Category Quantum field theory phys stub ... more details
In computer science , Constraint automata are a formalism to describe the behavior and possible data flow in coordination models ref http adsabs.harvard.edu abs 2009acse.book..972N Linear Temporal Logic of Constraint Automata by Sara Navidpour and Mohammad Izadi, Department of Mathematical Science, Sharif University of Technology, Tehran, Iran. ref . It was introduced by Arbab et al. ref http ftp.cwi.nl CWIreports SEN SEN R0309.pdf Effective Modeling of Software Architectural Assemblies Using Constraint Automata by Nikunj R. Mehta, Marjan Sirjani, and Farhad Arbab. Centrum Wiskunde & Informatica CWI Technical Report SEN R0309, October 22, 2003. ref as a variation of finite automata for model checking Reo connector circuits. Constraint automata can be considered generalizations of Probabilistic automaton probabilistic automata , in which data constraints, instead of probabilities, label state transitions and influence their firing. See also Model checking Finite automata Probabilistic automaton Colored Petri net References reflist Category Automata theory ... more details
Orphan date October 2011 In corporate governance , the outrage constraint is an upper limit on executive pay . ref name Krugman2002 Cite news last Krugman first Paul title The Outrage Constraint url http www.nytimes.com 2002 08 23 opinion the outrage constraint.html work The New York Times date 2002 08 23 accessdate 22 October 2011 quote In practice, modern C.E.O. s set their own compensation, limited only by the outrage constraint outrage not on the part of the board, whose members depend on the C.E.O. s good will for many of their perks, but on the part of outside groups that can make trouble. ref ref name BebchukFried2006 cite book author1 Lucian Arye Bebchuk author2 Jesse M. Fried title Pay Without Performance The Unfulfilled Promise of Executive Compensation url http books.google.com books?id JDDnbxaleNsC&pg PA65 accessdate 25 October 2011 date 1 September 2006 origyear Previous edition 2004 publisher Harvard University Press isbn 978 0 674 02228 7 page 65 quote When the potential outrage costs are large enough, they will deter the adoption of arrangements that managers would otherwise favor. We shall refer to arrangements that are deterred in this way as ones that violate the outrage constraint. ref ref Cite journal last Sheehan first Kym title Is the Outrage Constraint an Effective Constraint on Executive Remuneration? Evidence from the UK and Preliminary Results from Australia url http papers.ssrn.com sol3 papers.cfm?abstract id 974965 publisher Social Science Research Network date 2007 03 18 accessdate 23 October 2011 quote The managerial power thesis of Professors Lucian Bebchuk and Jesse Fried argues that outrage is perhaps the only effective constraint on executive remuneration, where the board of directors is effectively dominated by a sufficiently powerful CEO or senior management group. ref ref cite conference url http www.people.fas.harvard.edu idew papers ... over boards of directors and are mainly restricted by an outrage constraint where shareholders ... more details
Constraint Grammar CG is a methodological paradigm for Natural language processing NLP . Linguist written, context dependent rules are compiled into a grammar that assigns grammatical tags readings to words or other tokens in running text. Typical tags address lemmatisation lexeme or base form , inflexion , derivation linguistics derivation , syntactic function , dependency, Valency linguistics valency , case role s, semantic type etc. Each rule either adds, removes, selects or replaces a tag or a set of grammatical tags in a given sentence context. Context conditions can be linked to any tag or tag ... of a given kind, thus providing a high degree of robustness. The Constraint Grammar concept was launched ... treebank projects have used Constraint Grammar for automatic annotation. CG methodology has also used .... List of Constraint Grammar systems sorted by language Free software http beta.visl.sdu.dk cg3.html VISL CG 3 Constraint Grammar compiler parser Northern Sami language North and Lule Sami language ... constraint grammar.html DanGram English http www2.lingsoft.fi cgi bin engcg ENGCG , http www.ling.helsinki.fi avoutila cg index.html ENGCG 2 , http beta.visl.sdu.dk constraint grammar.html VISL ENGCG Esperanto http beta.visl.sdu.dk constraint grammar.html EspGram French http beta.visl.sdu.dk constraint grammar.html FrAG German http beta.visl.sdu.dk constraint grammar.html GerGram Irish ... Spanish http beta.visl.sdu.dk constraint grammar.html HISPAL Swedish http www2.lingsoft.fi doc swecg intro SWECG Swahili Portuguese http beta.visl.sdu.dk constraint grammar.html PALAVRAS External links http kevindonnelly.org.uk 2010 05 constraint grammar tutorial CG Tutorial by Kevin Donnelly http ... Bick, Eckhard. 2000. The Parsing System Palavras Automatic Grammatical Analysis of Portuguese in a Constraint .... Constraint Grammar as a Framework for Parsing Unrestricted Text. H. Karlgren, ed., Proceedings ..., Fred, Atro Voutilainen, Juha Heikkil , and Arto Anttila, editors. 1995. Constraint Grammar ... more details
Refimprove date December 2009 File Budget constraint.svg thumb 250px Budget constraint, where math A frac m P y math and math B frac m P x math A budget constraint represents the combinations of goods and services that a consumer can purchase given current prices with his or her income. Consumer theory uses the concepts of a budget constraint mathematics constraint and a preference map to analyze consumer choices. Both concepts have a ready Consumer Theory graphical representation in the two good case. Uses Individual choice File Indifference curves showing budget line.svg thumb right An individual should consume at Qx, Qy . An individual consumer should choose to consume goods at the point where the most preferred available indifference curve on their indifference curve Map and properties of indifference curves preference map is tangent to their budget constraint. That is, the indifference curve tangent to the budget constraint represents the maximum utility obtained utilizing the entire budget of the consumer. The tangent point the xy coordinate represents the amount of goods x and y the consumer should purchase to fully utilize their budget to obtain maximum utility. ref Lipsey 1975 . p 182. ref A line connecting all points of tangency between the indifference curve and the budget constraint is called the expansion path . ref name Salvatore Salvatore, Dominick 1989 . Schaum s outline ... constraints on production. A production possibility frontier is a budget constraint presented ... models of international trade, the budget constraint of the economy its CPF is determined by the terms ... between multiple goods through a budget constraint. In such a case, assuming there are math n , math ... constraint is math sum i 1 np ix i leq W. math Further, if the consumer spends his income entirely, the budget constraint binds math sum i 1 np ix i W. math In this case, the consumer cannot ... isbn 0297768999 DEFAULTSORT Budget Constraint Category Consumer theory Category Budgets Constraint Category ... more details
In constraint satisfaction , constrained optimization also called constraint optimization seeks for a solution maximizing or minimizing a cost function . Definition A constraint optimization problem can be defined as a regular constraint satisfaction problem in which constraints are weighted and the goal is to find a solution maximizing the weight of satisfied constraints. Alternatively, a constraint optimization problem can be defined as a regular constraint satisfaction problem augmented with a number of local cost functions. The aim of constraint optimization is to find a solution to the problem whose cost, evaluated as the sum of the cost functions, is maximized or minimized. The regular constraints are called hard constraints , while the cost functions are called soft constraints . These names ...,n math and math h j mathbf x le d j mathrm for j 1, cdots,m math are constraint functions that need to be satisfied. Solution methods Branch and bound Constraint optimization can be solved by branch ... each soft constraint separately. For each soft constraint, the maximal possible value for any ... constraints may derive from different evaluations a soft constraint may be maximal for math x a math while another constraint is maximal for math x b math . Russian doll search This method runs a branch ... elimination The bucket elimination algorithm can be adapted for constraint optimization. A given ... soft constraint. The cost of this new constraint is computed assuming a maximal value for every ... except math x math , the new soft constraint is defined by not exactly the correct notation, but clear ... constraints of the bucket are replaced as above to remove the variable. The resulting constraint is then placed in the appropriate bucket. See also Distributed constraint optimization Penalty method Lagrange multipliers References cite book first Rina last Dechter title Constraint Processing publisher ... 7 Category Mathematical optimization Category Constraint programming ... more details
Carrier s constraint is the observation that air breathing vertebrates which have two lungs and flex their bodies sideways during animal locomotion locomotion find it very difficult to move and breathe at the same time, because the sideways flexing expands one lung and compresses the other. this shunts stale air from lung to lung instead of expelling it completely to make room for fresh air. ref cite journal last Carrier first D.R. title The evolution of locomotor stamina in tetrapods circumventing a mechanical constraint journal Paleobiology volume issue 13 pages 326 341 year 1987 ref Consequences of Carrier s constraint Most lizards move in short bursts, with long pauses for breath. Around the Late Triassic period, animals with Carrier s constraint were preyed on by bipedal species that evolved a more efficient stride. Ways of avoiding Carrier s constraint Partial solutions Snake s have only one lung. It is not known how this lung operates during locomotion, other than that they can indeed move and breathe at the same time. Monitor lizard s increase their stamina by using bones and muscles in the throat and floor of the mouth to gulp air via buccal pumping . ref cite web url http biomechanics.bio.uci.edu html nh biomech monitor monitor.htm title Monitor Marathons year 2003 last Summers first A ref Crocodilians use a high walk , with a more erect limb posture that minimizes sideways flexing, to cross long distances. However, as they evolved from upright walkers with limited bipedality, this may simply be a remnant of past behavior rather than a specific adaptation to overcome this difficulty. Complete solutions Bird s have erect limbs and rigid bodies, and therefore do not flex sideways when moving. In addition many of them have a mechanism which pumps both lungs simultaneously when the birds rock their hips. Most mammal s have erect limbs and flexible bodies, which makes their bodies flex vertically when moving quickly. This aids breathing, as it expands and compresses ... more details
Unreferenced date July 2008 A liquidity constraint in economic theory is a form of imperfection in the capital market . It causes difficulties for models based on intertemporal consumption . Many economic models require individuals to Saving money save or borrow money from time to time. A liquidity constraint is an arbitrary limit on the amount an individual can borrow, or an arbitrary alteration in the interest rate they pay. By raising the costs of borrowing, they prevent individuals from fully optimising their behaviour over time. Actually existing liquidity constraints are mainly due to risk based behaviour by lenders such as bank s. Mortgage loan Mortgage lending is the cheapest way of an individual borrowing money, but is only available to people with enough savings to buy property. Because the loan is secured on a house or other property, it is only accessible to particular individuals those who have enough savings to put down a deposit . Other forms of credit, like loan unsecured loan s, credit card s and loan shark s, have progressively higher interest rates, and are used more by poorer people. econ stub Category Intertemporal economics ... more details
Unreferenced stub auto yes date December 2009 In theoretical physics , it is often important to study theories with the diffeomorphism symmetry such as general relativity . These theories are invariant under arbitrary coordinate transformations. Equations of motion are generally derived from the requirement that the group action action is stationary. There are special variations that are equivalent to spatial diffeomorphisms. The invariance of the action under these variations implies non dynamical equations of motion i.e. constraints. These equations must be satisfied or, at least, they must annihilate the physical states in a quantum version of the theory. See also Wheeler deWitt equation DEFAULTSORT Diffeomorphism Constraint Category Quantum gravity Category Diffeomorphisms Quantum stub ... more details
In mechanics , a constraint algorithm is a method for satisfying constraints for bodies that obey Newton ... novel unconstrained coordinates internal coordinates , introducing explicit constraint forces, and minimizing constraint forces implicitly by the technique of Lagrange multipliers or projection methods. Constraint algorithms are often applied to molecular dynamics simulations. Although such simulations ... angle constraints, they may also be carried out with explicit or implicit constraint forces for the bond lengths and bond angles. Explicit constraint forces typically shorten the time step significantly ... constraint solvers are generally preferred. Mathematical background The motion of a set of N particles ... coordinates. A second approach is to introduce explicit forces that work to maintain the constraint .... A third approach is to use a method such as Lagrange multipliers or projection to the constraint ..., internal coordinate constraint solvers were extended to molecular dynamics. ref name Bae Haug 1988a ... a the unconstrained positions are obtained after a simulation time step, b the gradients of each constraint ... of the two particles involved in the k th constraint at the time t and math d k math is the prescribed inter particle distance. These constraint equations, are added to the potential energy function ... lambda k sigma k t right , quad i 1 dots N. math Adding the constraint equations to the potential does ... 0. math This is repeated until the constraint equations math sigma k t Delta t math are satisfied up ... the system of non linear constraint equations using the Gauss Seidel method to approximate the solution ... the constraint equations math sigma k t Delta t math are solved to a given tolerance. Each iteration ... coauthors Berendsen HJC, Hirasawa K title A Noniterative Matrix Method for Constraint Molecular Dynamics ... last Forester first TR coauthors Smith W year 1998 title SHAKE, Rattle, and Roll Efficient Constraint ... on the particle velocities. Finally, MSHAKE computes corrections on the constraint forces , achieving ... more details
Unreferenced date June 2008 In law , time constraints are placed on certain lawsuit action s and Filing legal filings in the interest of speedy justice, and additionally to prevent the evasion of the ends of justice by waiting until a matter is Mootness law moot . The penalty for violating a legislative or court imposed time constraint may be anything from a small fine to judicial determination of an entire case against one s interests. For example, if a complaining party files an action and then fails to cause the papers pertaining thereto to be served on the opposing party within the time established by local rules, and is unable to convince the court that there was good and sufficient reason for the delay, he risks having his action dismissed with prejudice . If the opposing party is served with the papers and fails to respond within the time limit provided for his answer, he risks having the case decided against him by default law default . If one is aggrieved by the judicial outcome of an action and wishes to appeal , he may be forever barred from doing so if he fails to meet the deadline by which his appeal may be filed. By court order, or by local rule, there may be other time constraints. One may be required to answer interrogatories or a request to produce or other discovery law discovery pleading s within a given time. He may be required to give a certain number of days advance notice before he intends to deposition law depose a party disambiguation party or witness . A court may order that there will be only a certain number of weeks or months allowed during which the parties to an action may conduct discovery. There may be a limitation placed upon a Deposition law deposition , requiring that the party taking it conclude his questioning within a certain number of hours or days. See also Statute of limitations Statute of repose Category Civil procedure law term stub ... more details
In database systems, a propagation constraint details what should happen to a related table when we update a row or rows of a target table Paul Beynon Davies, 2004, p.108 . Tables are linked using primary key to foreign key relationships. It is possible for users to update one table in a relationship in such a way that the relationship is no longer consistent and this is known as breaking referential integrity . An example of breaking referential integrity if a table of employees includes a department number for Housewares which is a foreign key to a table of departments and a user deletes that department from the department table then Housewares employees records would refer to a non existent department number. Propagation constraints are methods used by relational database management system s RDBMS to solve this problem by ensuring that relationships between tables are preserved without error. In his database textbook, Beynon Davies explains the three ways that RDBMS handle deletions of target and related tuple s Restricted Delete the user cannot delete the target row until all rows that point to it via foreign key s have been deleted. This means that all Housewares employees would need to be deleted, or their departments changed, before removing the department from the departmental table. Cascades Delete can delete the target row and all rows that point to it via foreign keys are also deleted. The process is the same as a restricted delete, except that the RDBMS would delete the Houseware employees automatically before removing the department. Nullifies Delete can delete the target row and all foreign keys pointing to it are set to Null SQL null . In this case, after removing the housewares department, employees who worked in this department would have a Null SQL NULL unknown value for their department. Bibliography Beynon Davies, P. 2004 Database Systems Third Edition, Palgrave . Category Relational database management systems ... more details
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