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Il prestanome
Titolo originaleThe Front
Durata95'
Regia{{{regista}}}

Il prestanome è un film scritto da Walter Bernstein, diretto dal regista Martin Ritt, attori principali Woody Allen e Zero Mostel. Il film presenta una prospettiva dell'industria dell'intrattenimento negli Stati Uniti nei giorni del Maccartismo, quando molti attori, sospettati per attività sovversive in seguito ad un'indagine della House Committee on Un-American Activities, furono scritti nelle liste nere perdendo ogni possibilità di continuare il loro lavoro nel mondo dello spettacolo. La sceneggiatura fu scritta da Walter Bernstein, lui stesso vittima delle "Hollywood blacklist", così come lo furono Ritt e i membri del cast Mostel ed Herschel Bernardi. Walter Bernstein fu inserito nelle black list dopo che il suo nome venne elencato nel "Red Channels", un giornale pubblicato dall'FBI che elencava i nomi dei comunisti o dei simpatizzanti del comunismo.

Trama[modifica | modifica wikitesto]

Woody Allen è un modesto allibratore che presta il suo nome ai soggetti di un suo amico finito nelle blacklist; questa infatti era una tattica usata da parecchi delle Hollywood blacklist. Probabilmente per difendersi dalla censura, il film riguarda le blacklist nelle industrie televisive e dei nightclub piuttosto che quelle cinematografiche. E' ambientato nei primi anni 50, a New York. Howard Prince (Woody Allen) lavora come cassiere in un ristorante e per arrotondare lo stipendio svolge come secondo lavoro quello di allibratore. Un suo amico, Alfred Miller (Michael Murphy) è uno sceneggiatore blacklistato; avvicina Howard e gli propone di diventare un front man, un prestanome, e utilizza il nome di Howard per presentare le sue sceneggiature ad una stazione televisiva.

Howard viene presentato come un uomo senza alcun interesse politico ma bisognoso di soldi, così accetta subito di aiutare Miller. Appena Prince colleziona più di un successo in televisione, gli altri amici di Miller iniziano anche loro a servirsi di lui come prestanome. Il film descrive anche la tragica morte di Hecky Brown (Zero Mostel), un attore affermato che, una volta finito nelle blacklist, era rimasto senza senza soldi e senza più rispetto nel mondo dello spettacolo.

As Howard witnesses the terrible actions of the “Freedom Information Services” and is bombarded with the harsh realities of his friends who must live in secrecy for their past and at times present involvement with leftist political groups, Howard himself is put to the test. He must go in front of the “Freedom Information Services” committee and name names and the audience witnesses Howard’s valiant response to the committee’s insulting mental tortures.

Historical Context[modifica | modifica wikitesto]

Agli inizi del 1947, la House Committee on Unamerican Activities (HUAC) iniziò le indagini ufficiali sulla penetrazione del Partito Comunista degli Stati Uniti nell'industria cinematografica di Hollywood. Queste indagini furno svolte in maniera più massiccia tra il 1947 e il 1951, con interrogatori e controlli continui da parte dell'FBI ad attori, direttori e scrittori. Il gruppo più infame che perpetrava queste denuce divenne noto come "The Hoolywood Ten"; bisogna ricordare che l'HUAC non mirava soltanto al partito comunista ma anche a socialisti, radicali di sinistra e tutti colori che furono coinvolti in qualche modo con il gruppo politico che aveva opinioni contrarie a coloro che erano al potere a quell'epoca.

Critical response[modifica | modifica wikitesto]

La maggior parte delle risposte dei critici de Il prestanome furono mischiate tra quelli che Much critical response to The Front was mixed between those who felt that the film effectively (and amusingly) dealt with the political topic at hand, and those who felt that it glossed over its potential to make a strong statement about the McCarthy era. In his 1976 review for the New York Times, Vincent Canby acknowledged the movie's lack of intense political commentary. He wrote, "The Front is not the whole story of an especially unpleasant piece of American history. It may be faulted for oversimplification. Mr. Ritt and Mr. Bernstein, both veterans of the blacklist, are not interested in subtleties. Yet even in its comic moments The Front works on the conscience. It recreates the awful noise of ignorance that can still be heard" (Canby,1976). Canby felt that while the film may not directly attack or address the political era, it still managed to get its message across - the message, it seems, being not to rat people out. Furthermore, Canby emphasized that the film managed to encourage the audience to understand the emotional effects of blacklisting and finger-pointing through its concentration on single characters' experiences.

On the other hand, Roger Ebert, in his 1976 review of the film, dismissed the political value of The Front, stating instead that "What we get are the adventures of a schlemiel in wonderland." Ebert felt that Woody Allen's character was too comedic and unconvincing as a writer to really represent the true nature of "front" writers. Ebert wrote that it would be unrealistic to think that Howard Prince could ever be taken seriously as a writer by those in the television industry. However, Ebert did write that the Hecky Brown character was a worthwhile element of the film - "The tragedy implied by this character tells us what we need to know about the blacklist's effect on people's lives; the rest of the movie adds almost nothing else" (Ebert, 1976). It should be noted that Ebert's interpretation is at odds with the consensus of the fourteen critics tracked by Rotten Tomatoes, where the film scores 93%. [1]

Walter Bernstein was nominated for the 1977 Academy Award for Writing Original Screenplay and Zero Mostel was nominated for a BAFTA Award for Best Supporting Actor.

Collegamenti esterni[modifica | modifica wikitesto]


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[[Categoria:film commedia|Prestanome, Il]]

Da tradurre: http://en.wikipedia.org/wiki/Electrical_breakdown

This article contains specific implementations of fault tolerant systems. For general theory, see fault-tolerant design.

La Fault-tolerance (nota in inglese anche come graceful degradation) è la proprietà che consente ad un sistema di continuare a funzionare correttamente in caso di fallimento di qualche sua componente. Se la sua qualità elaborativa diminuisce del tutto, tale diminuzione è proporzionale alla severità del fallimento; a differenza di quanto avviene nei sistemi progettati in modo ingenuo, ove un piccolo fallimento può causare un breakdown (elettrico totale. La fault-tolerance è particolarmente ricercata nei sistemi con alta availability o nei sistemi critici.


Fault-tolerance is not just a property of individual machines; it may also characterise the rules by which they interact. For example, the Transmission Control Protocol is designed to allow reliable two-way communication in a packet-switched network, even in the presence of communications links which are imperfect or overloaded. It does this by requiring the endpoints of the communication to expect packet loss, duplication, reordering and corruption, so that these conditions do not damage data integrity, and only reduce throughput by a proportional amount.

Data formats may also be designed to degrade gracefully. HTML for example, is designed to be forward compatible, allowing new HTML entities to be ignored by browsers which do not understand them without causing the document to be unusable.

Recovery from errors in fault-tolerant systems can be characterised as either roll-forward or roll-back. When the system detects that it has made an error, roll-forward recovery takes the system state at that time and corrects it, to be able to move forward. Roll-back recovery reverts the system state back to some earlier, correct version, for example using checkpointing, and moves forward from there. Roll-back recovery requires that the operations between the checkpoint and the detected erroneous state can be made idempotent. Some systems make use of both roll-forward and roll-back recovery for different errors or different parts of one error.

Within the scope of an individual system, fault-tolerance can be achieved by anticipating exceptional conditions and building the system to cope with them, and, in general, aiming for self-stabilization so that the system converges towards an error-free state. However, if the consequences of a system failure are catastrophic, or the cost of making it sufficiently reliable is very high, a better solution may be to use some form of duplication.

Fault-tolerance by duplication[modifica | modifica wikitesto]

Duplication can give fault-tolerance in three ways:

  • Replication: Providing multiple identical instances of the same system, directing tasks or requests to all of them in parallel, and choosing the correct result on the basis of a quorum;
  • Redundancy: Providing multiple identical instances of the same system and switching to one of the remaining instances in case of a failure (fall-back or backup);
  • Diversity: Providing multiple different implementations of the same specification, and using them like replicated systems to cope with errors in a specific implementation.

A redundant array of independent disks (RAID) is an example of a fault-tolerant storage device that uses redundancy.

A lockstep fault-tolerant machine uses replicated elements operating in parallel. At any time, all the replications of each element should be in the same state. The same inputs are provided to each replication, and the same outputs are expected. The outputs of the replications are compared using a voting circuit. A machine with two replications of each element is termed dual modular redundant (DMR). The voting circuit can then only detect a mismatch and recovery relies on other methods. A machine with three replications of each element is termed triple modular redundant (TMR). The voting circuit can determine which replication is in error when a two-to-one vote is observed. In this case, the voting circuit can output the correct result, and discard the erroneous version. After this, the internal state of the erroneous replication is assumed to be different from that of the other two, and the voting circuit can switch to a DMR mode. This model can be applied to any larger number of replications.

Lockstep fault tolerant machines are most easily made fully synchronous, with each gate of each replication making the same state transition on the same edge of the clock, and the clocks to the replications being exactly in phase. However, it is possible to build lockstep systems without this requirement.

Bringing the replications into synchrony requires making their internal stored states the same. They can be started from a fixed initial state, such as the reset state. Alternatively, the internal state of one replicant can be copied to another replicant.

One variant of DMR is pair-and-spare. Two replicated elements operate in lockstep as a pair, with a voting circuit that detects any mismatch between their operations and outputs a signal indicating that there is an error. Another pair operates exactly similarly. A final circuit selects the output of the pair that does not proclaim that it is in error. Pair-and-spare requires four replicants rather than the three of TMR, but has been used commercially.

See also[modifica | modifica wikitesto]

Bibliography[modifica | modifica wikitesto]

External links[modifica | modifica wikitesto]

it:Tolleranza ai guasti

Template:Dablink Fault tolerant design refers to a method for designing a system so it will continue to operate, possibly at a reduced level (also known as "graceful degradation"), rather than failing completely, when some part of the system fails. The term is most commonly used to describe computer-based systems designed to continue more or less fully operational with, perhaps, a reduction in throughput or response time in the event of some partial failure. That is, the system as a whole is not stopped due to problems either in the hardware or the software. An example in another field is a motor vehicle designed so it will continue to be drivable if one of the tires is punctured.

Methods[modifica | modifica wikitesto]

  • Fault-tolerant components. If each component, in turn, can continue to function when one of its subcomponents fails, this will allow the total system to continue to operate, as well. Using the motor vehicle example, some cars have "run flat" tires, which contain a solid rubber core that allows them to be used if the surface is punctured. They can only be used for a limited time at a reduced speed, but this is still a substantial improvement over traditional tires.
  • Redundancy. This means having backup components which automatically "kick in" should one component fail. For example, large cargo trucks can lose a tire without any major consequences. They have so many tires that no one tire is critical (with the exception of the front tires, which are used to steer).

Disadvantages[modifica | modifica wikitesto]

The advantages of fault tolerant design are obvious, while many of the disadvantages are not:

  • Interference with fault detection in the same component. To continue the same example, it may not be obvious to the driver when a tire has been punctured, with either of the fault tolerant systems. This is usually handled with a separate "automated fault detection system". In the case of the tire, an air pressure monitor detects the loss of pressure and notifies the driver. The alternative is a "manual fault detection system", such as manually inspecting all tires at each stop.
  • Interference with fault detection in another component. Another variation of this problem is when fault tolerance in one component prevents fault detection in a different component. For example, if component B performs some operation based on the output from component A, then fault tolerance in B can hide a problem with A. If component B is later changed (to a less fault tolerant design) the system may fail suddenly, making it appear that the new component B is the problem. Only after the system has been carefully scrutinized will it become clear that the root problem is actually with component A.
  • Reduction of priority of fault correction. Even if the operator is aware of the fault, having a fault tolerant system is likely to reduce the importance of repairing the fault. If the faults are not corrected, this will eventually lead to system failure, when the fault tolerant component fails completely or when all redundant components have also failed.
  • Test difficulty. For certain critical fault tolerant systems, such as a nuclear reactor, there is no easy way to verify that the backup components are functional. The most infamous example of this is Černobyl', where operators tested the emergency backup cooling by disabling primary and secondary cooling. The backup failed, resulting in a core meltdown and massive release of radiation.
  • Cost. Both fault tolerant components and redundant components tend to increase cost. This can be a purely economic cost or can include other measures, such as weight. Manned spaceships, for example, have so many redundant and fault tolerant components that their weight is increased dramatically over unmanned systems, which don't require the same level of safety.
  • Inferior components. A fault-tolerant design may allow for the use of inferior components, which would have otherwise made the system inoperable. While this practice has the potential to mitigate the cost increase, use of multiple inferior components may lower the reliability of the system to a level equal to, or even worse than, a comparable non-fault-tolerant system.

When to use fault-tolerant design[modifica | modifica wikitesto]

Providing fault-tolerant design for every component is normally not an option. In such cases the following criteria may be used to determine which components should be fault tolerant:

  • How critical is the component? In a car, the radio isn't critical, so this component has less need for fault tolerance.
  • How likely is the component to fail ? Some components, like the drive shaft in a car, are not likely to fail, so no fault tolerance is needed.
  • How expensive is it to make the component fault tolerant ? Requiring a redundant car engine, for example, would likely be too expensive both economically and in terms of weight and space, to be considered.

An example of a component that passes all the tests is a car's occupant restraint system. While we don't normally think of the primary occupant restraint system, it is gravity. If the vehicle rolls over or undergoes severe g-forces, then this primary method of occupant restraint may fail. Restraining the occupants during such an accident is absolutely critical to safety, so we pass the first test. Accidents causing occupant ejection were quite common before seat belts, so we pass the second test. The cost of a redundant restraint method like seat belts is quite low, both economically and in terms or weight and space, so we pass the third test. Therefore, adding seat belts to all vehicles is an excellent idea. Other "supplemental restraint systems", such as airbags, are more expensive so may not pass that test. This is why inexpensive vehicles typically have fewer airbags than expensive vehicles.

Examples[modifica | modifica wikitesto]

Hardware fault tolerance sometimes requires that broken parts can be swapped out with new ones while the system is still operational. Such a system implemented with a single backup is known as single point tolerant, and represents the vast majority of fault tolerant systems. In such systems the mean time between failures should be long enough for the operators to have time to fix the broken devices before the backup also fails. It helps if the time between failures is as long as possible, but this is not specifically required in a fault tolerant system.

Fault tolerance is notably successful in computer applications. Tandem Computers built their entire business on such machines, which used single point tolerance to create their NonStop systems with uptimes measured in decades.

Related terms[modifica | modifica wikitesto]

There is a difference between fault tolerance (systems that work even when a fault occurs) and systems that rarely have problems. For instance, the Western Electric crossbar systems had failure rates of two hours per forty years, and therefore were highly fault resistant. But when a fault did occur they still stopped operating completely, and therefore were not fault tolerant.

External links[modifica | modifica wikitesto]

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