Nondeterminism may refer to Nondeterministic programming computer science Nondeterministic algorithm computer science Non deterministic Turing machine computer science Indeterminacy in computation disambiguation Indeterminism philosophy See also Indeterminacy disambiguation disambig ... more details
In computer science , unbounded nondeterminism or unbounded indeterminacy is a property of Concurrency ... will eventually be serviced . Unbounded nondeterminism became an important issue in the development ... Discussion of unbounded nondeterminism tends to get involved with discussions of fairness ... of fair or unbounded nondeterminism in the merging of strings was given by William D. Clinger, in his ... data flow program operating on streams. On the possibility of implementing unbounded nondeterminism Edsger Dijkstra 1976 argued that it is impossible to implement systems with unbounded nondeterminism ... fair. Nondeterministic automata Nondeterministic Turing machine s have only bounded nondeterminism. Likewise sequential programs containing guarded commands as the only sources of nondeterminism have only bounded nondeterminism Edsger Dijkstra 1976 . Briefly, choice nondeterminism is bounded ... from the interpretation given to choice points. This premise fails for arrival nondeterminism in the arrival ... computation. Unbounded nondeterminism and noncomputability Spaan et al. 1989 have argued that it is possible ... for dealing with unbounded nondeterminism Clinger and Carl Hewitt Citation needed date September ... of unbounded nondeterminism built in Clinger 1981 Hewitt 1985 Hewitt and Agha 1991 Hewitt 2006b this allows ... in concurrent computation . Hewitt 2006 justified his use of unbounded nondeterminism by arguing ... number of states. He further argued that Electronic mail enables unbounded nondeterminism since .... This gave rise to the Actor model Unbounded nondeterminism controversy Unbounded nondeterminism ... versions. All of these models have the property of bounded nondeterminism if a machine always ... it can halt. Hewitt argued that there is a fundamental difference between choices in global state nondeterminism and the arrival order indeterminacy nondeterminism of his Actor model . In global state nondeterminism, a choice is made for the next global state. In arrival order indeterminacy, arbitration ... more details
Indeterminancy in computation may refer to Quantum indeterminacy in quantum computer s Nondeterministic finite automata Nondeterministic algorithm In concurrency Indeterminacy in concurrent computation Unbounded nondeterminism disambig ... more details
wikt fairness Fairness or being fair may refer to Equity law , a legal principle allowing for the use of discretion and fairness when applying justice Social justice , equality and solidarity in a society Distributive justice , equal allocation of goods in a society Fairness, absence of bias in specific realms In American broadcasting, presentation of controversies in accord with the Fairness Doctrine In computer science, Unbounded nondeterminism Fairness fairness is a property of unbounded nondeterminism In network engineering, access to resources formally rated by a fairness measure In game theory, abstract principles for achieving fair division game theoretic concept also known as cake cutting algorithms In economics, relation among economic factors where price matches fair value that is not only bias free but also rational Fairness of human pigmentation, Human skin color Skin tone variability relatively light coloring, especially of skin Being fair, property of motion of a batted baseball that qualifies it as a fair ball disambig fr quit ... more details
wiktionary Indeterminacy refers to uncertainty in knowledge, either in its precision or its predictability. Indeterminacy or underdeterminacy may refer to Indeterminacy in computation disambiguation aleatoric music and indeterminacy in music . Statically indeterminate Indeterminacy literature a literary term In set theory and game theory, the opposite of determinacy Underdetermined system In law Indeterminacy debate in legal theory Underdeterminacy law In linguistics Indeterminacy of translation Referential indeterminacy In philosophy Indeterminacy philosophy Indeterminism , the belief that not all events are causally determined Deterministic system philosophy Philosophy of science Indeterminacy of theory under empirical testing Underdetermination In physics Quantum indeterminacy Uncertainty principle Scientific determinism See also Nondeterminism disambiguation Determinism disambiguation Indeterminate disambiguation disambig ... more details
In computational complexity theory complexity theory , ZPL Zero error Probabilistic Logarithmic space is the set of problems solvable by a probabilistic Turing machine which always yields the correct answer and uses logarithmic space on average. Probabilistic algorithms that always give the correct answer are called Las Vegas algorithm s. Unlike its deterministic counterpart L complexity L , a ZPL machine can potentially use exponential time by exploiting randomness. If ZPL is restricted to polynomial time, we get the more interesting class ZPLP complexity ZPLP . A surprising result is that ZPL is equal to both RL complexity RL and NL complexity NL thus, if a problem can be solved in logarithmic space with nondeterminism or with one sided error, it can be solved with no error and logarithmic space on average. See the articles on RL complexity RL and NL complexity NL for more information about ZPL. Category Probabilistic complexity classes comp sci theory stub ... more details
Expert subject Computer science date September 2008 Cleanup date September 2008 Definition of Symmetric Turing machines A Symmetric TM is a TM which has a configuration graph that is undirected. That is configuration i yields configuration j if and only if j yields i. The set of languages that have a symmetric TM deciding it in log space is called SL complexity SL . It was first defined in 1982 by Lewis and Papadimitriou, ref Jesper Jansson. http www.df.lth.se jj Publications STCON2.ps Deterministic Space Bounded Graph Connectivity Algorithms . Manuscript. 1998. ref ref Harry R. Lewis and Christos H. Papadimitriou. Symmetric space bounded computation. Theoretical Computer Science . pp.161 187. 1982. ref who were looking for a class in which to place USTCON, which until this time could, at best, be placed only in NL complexity NL , despite seeming not to require nondeterminism. They defined the symmetric Turing machine, used it to define SL. Symmetric Turing machines are kind of Turing machines with limited nondeterministic power. Informally Symmetric computations are reversible in an approximate manner. A symmetric computation is divided into locally deterministic sub computation segments between special configuration, where nondeterminism takes place, such that the only special configuration reached from a backward computation is the special configuration started the segment. Thus the segments are locally deterministic in its forward direction and have limited nondeterminism in its backward direction. Also if there is a way from special configuration A1 to special configuration A2, there must be a way back from A2 to A1. http moustafaemara.wordpress.com files 2008 07 smturing.png Example of Symmetric Configuration Symmetric log space complexity SSPACE S n is the class of the languages accepted by a symmetric Turing machine running in space O S n SL is the class of problems solvable by a nondeterministic Turing machine in logarithmic space, such that If the answer i ... more details
Unreferenced auto yes date December 2009 In computer science , a graph structured stack is a directed acyclic graph where each directed Path graph theory path represents a Stack data structure stack . The graph structured stack is an essential part of GLR parser Tomita s algorithm , where it replaces the usual Stack data structure stack of a pushdown automaton . This allows the algorithm to encode the nondeterministic choices in parsing an ambiguous grammar , sometimes with greater efficiency. In the following diagram, there are four stacks 7,3,1,0 , 7,4,1,0 , 7,5,2,0 , and 8,6,2,0 . Image Graph structured stack 1 jaredwf.png Graph structured stack 1 jaredwf.png Another way to simulate nondeterminism would be to duplicate the stack as needed. The duplication would be less efficient since vertices would not be shared. For this example, 16 vertices would be needed instead of 9. Image Stacks jaredwf.png Stacks jaredwf.png DEFAULTSORT Graph Structured Stack Category Graph data structures Comp sci stub it Graph structured stack ... more details
In computer science , Hennessy Milner logic HML is a multimodal logic used to specify properties of a labeled transition system , a structure similar to an automaton. It was introduced in 1980 by Matthew Hennessy and Robin Milner in their paper On observing nondeterminism and concurrency ICALP . Syntax A formula is defined by the following BNF grammar for L some set of actions math Phi tt , , , , , ,ff , , , , , , Phi 1 land Phi 2 , , , , , , Phi 1 lor Phi 2 , , , , , , L Phi , , , , , , langle L rangle Phi math That is, a formula can be constant truth always true constant false always false formula logical conjunction conjunction formula logical disjunction disjunction math scriptstyle L Phi math formula for all L derivatives, must hold math scriptstyle langle L rangle Phi math formula for some L derivative, must hold See also The modal calculus extends HML with fixed point operator s. Dynamic logic modal logic Dynamic logic , a multimodal logic with infinitely many modalities. References cite book author Colin P. Stirling title Modal and temporal properties of processes year 2001 publisher Springer isbn 9780387987170 pages 32 39 comp sci stub Category Concurrency Category Formal specification Category Modal logic Category Logic in computer science ... more details
Transaction logic is an extension of predicate logic with both declarative and procedural semantics that describe state changes in logic programming over dynamic database s. First proposed in the early 1990s by Anthony J. Bonner and Michael Kifer, transaction logic allows for the amalgamation property amalgamation of features including hypothetical updating, nondeterminism , and artificial intelligence via behaviors of object oriented databases. ref Bonner and Kifer 1995 , abstract ref Bonner and Kifer have offered a proof of completeness for a Serial Horn program implementation of transaction logic. ref Bonner and Kifer 1995 , 6. Proof Theory and appendix E ref A prototype of transaction logic has been implemented in XSB XSB Prolog . ref nowiki ftp ftp.cs.toronto.edu pub goku transaction logic XSB Prototype3 nowiki ref Notes references References Bonner, Anthony J. and Michael Kifer 1995 Transaction logic programming , Computer Systems Research Institute Technical Report CSRI 323 revision of CSRI 270 of 1992 , University of Toronto. Category Logic programming languages comp sci theory stub ... more details
PlusCal formerly known as Cal is an ALGOL algorithmic language . It is designed to replace pseudocode . PlusCal can express both Sequential algorithm sequential and concurrent algorithm s and features means to handle Nondeterministic algorithm nondeterminism , Atomicity programming atomicity and model checking . ref name Lamport2009 cite web url http research.microsoft.com en us um people lamport pubs pluscal.pdf title The PlusCal Algorithm Language last Lamport first Leslie date 2 January 2009 publisher Microsoft Research accessdate 17 September 2010 ref Syntax PlusCal expressions are written using TLA . ref name Lamport2009 The balance of PlusCal syntax can be translated to TLA ref cite web url http www.tlaplus.net tools title TLA Tools accessdate 2010 09 17 ref for the purposes of debugging and model checking. References Reflist External links http research.microsoft.com en us um people lamport tla pluscal.html PlusCal homepage at Microsoft Research Comp sci stub Category Algorithm description languages ... more details
Calculus of Broadcasting Systems CBS is a calculus of communicating systems CCS like process calculus calculus where Process computing processes speak one at a time and each is heard instantaneously by all others. Speech is autonomous, contention between speakers being resolved nondeterminism nondeterministically , but hearing only happens when someone else speaks. Observationally meaningful laws differ from those of CCS. The handshake communication of CCS is changed to broadcast communication in CBS. This allows several additional features Priority, which attaches only to autonomous actions, is simply added to CBS in contrast to CCS, where such actions are the result of communication. A CBS simulator runs a process by returning a list of values it broadcasts. This permits a powerful combination, CBS with the host language. It yields several elegant algorithms. Only processes with a unique response to each input are needed in practice, so weak bisimulation is a congruence. CBS subsystems are interfaced by translators by mapping messages to silence, these can restrict hearing and hide speech. Reversing a translator turns its scope inside out. This permits a new specification for a communication link &ndash the environment of each user should behave like the other user. See also Pi calculus Calculus of communicating systems CCS Communicating sequential processes CSP Bisimulation Alternating bit protocol References K. V. S. Prasad http www.cs.chalmers.se prasad scp.html A Calculus of Broadcasting Systems , Science of Computer Programming, 25, 1995. K. V. S. Prasad Programming with broadcasts , Lecture Notes in Computer Science , Vol. 715, CONCUR, 1993, Springer Science Business Media Springer Verlag . K. V. S. Prasad Broadcasting in time , Lecture Notes in Computer Science , Vol. 1061, COORDINATION, 1996, Springer Science Business Media Springer Verlag . External links http citeseer.nj.nec.com prasad95calculus.html Citations from CiteSeer http citeseer.nj.nec.com 32888 ... more details
Unreferenced stub auto yes date December 2009 In computational complexity theory , the complexity class NSPACE f n is the set of decision problem s that can be solved by a non deterministic Turing machine using space O f n , and unlimited time. It is the non deterministic counterpart of DSPACE . Several important complexity classes can be defined in terms of NSPACE . These include regular language REG DSPACE O 1 NSPACE O 1 , where REG is the class of regular language s nondeterminism does not add power in constant space . NL complexity NL NSPACE O log n context sensitive language CSL NSPACE O n , where CSL is the class of context sensitive language s. PSPACE NPSPACE math bigcup k in mathbb N mbox NSPACE n k math EXPSPACE NEXPSPACE math bigcup k in mathbb N mbox NSPACE 2 n k math The last two results above follow from Savitch s theorem , which states that for any function f n log n , NSPACE f n DSPACE f sup 2 sup n . The Immerman Szelepcs nyi theorem states that NSPACE s n is closed under complement for every function nowrap s n log n . NSPACE can be related to DTIME as follows. For any space constructible function s n , math mbox NSPACE s n subseteq bigcup k geq 1 mbox DTIME 2 k cdot s n math A futher generalization is ASPACE , defined with alternation complexity alternating Turing machines . References ComplexityZoo NSPACE f n N nspace . ComplexityClasses DEFAULTSORT Nspace Category Complexity classes Category Computational resources Comp sci theory stub de NSPACE es NSPACE ja NSPACE pt NSPACE zh NSPACE ... more details
In computational complexity theory , the complexity class FNP is the function problem extension of the decision problem class NP complexity NP . The name is somewhat of a misnomer, since technically it is a class of binary relation s, not functions, as the following formal definition explains A binary relation P x , y , where y is at most polynomially longer than x , is in FNP if and only if there is a deterministic not nondeterministic polynomial time algorithm that can determine whether P x , y holds given both x and y . This definition does not involve nondeterminism and is analogous to the verifier definition of NP . See FP complexity FP for an explanation of the distinction between FP and FNP . There is an NP language directly corresponding to every FNP relation, sometimes called the decision problem induced by or corresponding to said FNP relation. It is the language formed by taking all the x for which P x , y holds given some y however, there may be more than one FNP relation for a particular decision problem. Many problems in NP , including many NP complete problems, ask whether a particular object exists, such as a satisfying assignment, a graph coloring, or a clique of a certain size. The FNP versions of these problems ask not only if it exists but what its value is if it does. This means that the FNP version of every NP complete problem is NP hard . Bellare and Goldwasser showed in 1994 using some standard assumptions that there exist problems in NP such that their FNP versions are not self reducibility self reducible , implying that they are harder than their corresponding decision problem. FP FNP if and only if P NP problem P NP . See also TFNP References refbegin Elaine Rich, Automata, computability and complexity theory and applications , Prentice Hall, 2008, ISBN 0132288060, section 28.10 The problem classes FP and FNP , pp. 689 694 M. Bellare and S. Goldwasser. http citeseerx.ist.psu.edu viewdoc summary?doi 10.1.1.117.4445 The complexity of decisio ... more details
Hidden algebra provides a formal semantics for use in the field of software engineering , especially for concurrent distributed object system s. ref name homepage cite web url http cseweb.ucsd.edu goguen projs halg.html title Hidden Algebra Homepage publisher University of California, San Diego , USA accessdate September 26, 2011 authorlink Joseph Goguen first Joseph last Goguen ref It supports correctness proof s. ref cite web url http www.csc.liv.ac.uk grant Research Alg HA index.html title Hidden Algebra Behavioural specification and proof for systems with state publisher University of London , UK date July 31, 2006 accessdate September 26, 2011 author Malcolm, Grant ref Hidden algebra was studied by Joseph Goguen . ref name homepage ref cite paper url http dl.acm.org citation.cfm?id 340889 title Hidden algebra and concurrent distributed software publisher ACM , USA work ACM SIGSOFT Software Engineering Notes volume 25 number 1 date January 2000 doi 10.1145 340855.340889 accessdate September 26, 2011 authorlink Joseph Goguen first Joseph last Goguen ref It handles features of large software based systems, including concurrency , Distributed system distribution , nondeterminism , and local state s. It also handled object oriented features like class computer programming classes , Subclass computer science subclasses Inheritance object oriented programming inheritance , Attribute computing attributes , and Method computer programming methods . Hidden algebra generalizes process algebra and transition system approaches. References reflist External links http cseweb.ucsd.edu groups tatami handdemos doc haidx.htm Hidden Algebra Tutorial software eng stub Category Abstract algebra Category Universal algebra Category Logical calculi Category Concurrent computing Category Distributed computing ... more details
to run the algorithm is proportional to the degree of nondeterminism in the grammar on deterministic ... are deterministic or nearly deterministic, meaning that any nondeterminism is usually resolved ... more details
de Roever. Semantics of nondeterminism, concurrency, and communication Journal of Computer ... of Unbounded Nondeterminism ICALP 1980. David Park. On the semantics of fair parallelism Proceedings ... more details
and receiving a message. The semantics provided bounded nondeterminism unlike the Actor model with unbounded nondeterminism. However, with bounded nondeterminism is impossible for a server to guarantee ... with an already known process. The model of CSP deliberately had bounded nondeterminism Francez, Hoare, Lehmann, and de Roever 1979 whereas the Actor model had unbounded nondeterminism . Dijkstra 1976 had convinced Hoare that a programming language with unbounded nondeterminism could not be implemented ... the first denotational Actor model for concurrent computation that embodied unbounded nondeterminism ... more details
. Unbounded nondeterminism Asynchronously, different subsystems can come up and go down and communication ... the time that it will take to complete an operation cannot be bounded in advance see unbounded nondeterminism ... see unbounded nondeterminism . Recent developments Recent developments in the Actor model ... more details
Unreferenced date December 2009 Temporal multithreading is one of the two main forms of Multithreading computer architecture multithreading that can be implemented on computer processor hardware, the other being simultaneous multithreading . The distinguishing difference between the two forms is the maximum number of concurrent Thread computer science threads that can execute in any given Pipeline computing pipeline stage in a given Instruction cycle cycle . In temporal multithreading the number is one, while in simultaneous multithreading the number is greater than one. Variations There are many possible variations of temporal multithreading, but most can be classified into two sub forms Granularity coarse grained and fine grained. In coarse grained temporal multithreading, the main processor pipeline contains only one thread at a time. The processor must effectively perform a rapid context switch before executing a different thread. This fast context switch is sometimes referred to as a thread switch . There may or may not be additional penalty cycles when switching. There are many possible variations of coarse grained temporal multithreading, mainly concerning the algorithm that determines when thread switching occurs. This algorithm may be based on one or more of many different factors, including cycle counts, Cache miss Cache Misses cache misses , and Unbounded nondeterminism Fairness fairness . In fine grained temporal multithreading, the main processor pipeline may contain multiple threads, with context switches effectively occurring between pipe stages e.g. in the barrel processor . This form of multithreading can be more expensive than the coarse grained forms because execution resources that span multiple pipe stages may have to deal with multiple threads. Also contributing to cost is the fact that this design cannot be optimized around the concept of a background thread &mdash any of the concurrent threads implemented by the hardware might require its Sta ... more details
Data transformation refimprove date September 2010 In formal methods , program refinement is the formal verification verifiable transformation of an abstract high level formal specification into a concrete low level executable program . fact date September 2010 Stepwise refinement allows this process to be done in stages. Logically, refinement normally involves implication , but there can be additional complications. Data refinement Data refinement REDIRECTs HERE is used to convert an abstract data model in terms of set mathematics set s for example into implementable data structures such as Array data structure arrays . fact date September 2010 Operation refinement converts a specification of an operation on a system into an implementable computer program program e.g., a Procedure computer science procedure . The postcondition can be strengthened and or the precondition weakened in this process. This reduces any Nondeterministic algorithm nondeterminism in the specification, typically to a completely deterministic implementation. For example, x 1,2,3 where x is the value of the Variable programming variable x after an operation could be refined to x 1,2 , then x 1 , and implemented as x 1. Implementations of x 2 and x 3 would be equally acceptable in this case, using a different route for the refinement. However, we must be careful not to refine to x equivalent to false since this is unimplementable it is impossible to select a Element mathematics member from the empty set . The term Reification computer science reification is also sometimes used coined by Cliff Jones computer scientist Cliff Jones . Retrenchment computing Retrenchment is an alternative technique when formal refinement is not possible. The opposite of refinement is Abstraction computer science abstraction . Algorithm refinement Refinement calculus is a formal system inspired from Hoare logic that promotes program refinement. The FermaT Transformation System is an industrial strength implementation ... more details
Encyclopedia
top
