Praxis Mac OS

1. Praxis Core Preparation is an online Exam Prep class that you can take at your own pace. Mac: OS X Snow Leopard 10.6 or later. Browser: The latest version of Google Chrome or Mozilla Firefox are preferred. Microsoft Edge and Safari are also compatible. Adobe Acrobat Reader.
2. Praxis covers 4 primary aspects that all link together seamlessly – a Body of Knowledge (similar to APM / PMI), a method (similar to PRINCE2 / MSP), a competency framework AND a maturity capability assessment model (similar to P3M3). It really is a complete offering.

Registration

The at home testing option is available to anyone who meets the following requirements:

And like Demos, Praxis is a flexible and legible typeface that works well in small point sizes and on low-quality paper (office documents, newsletters, newspapers, etc.). The word 'Praxis' comes from Greek, and means 'a practical application.'

1. You live in the United States or a U.S. territory. Note: The ability to register for a Praxis test at home is based on the address in your Praxis account.
2. Your test title is offered for at home testing.
3. Your computer meets the equipment requirements for the test, including the installation of the ETS Test Browser for Windows^® or Mac^® and the ProctorU^® Equipment Check.
4. You have a room that provides an acceptable environment for the test.

First, verify that you meet the Equipment and Environment Requirements. Then, register via your Praxis account to schedule and purchase your test.

Yes. Accommodations of extended time, extra breaks, screen magnification and selectable colors can be requested using your Praxis account. Other accommodations available at physical testing centers can be requested through ETS Disability Services. All accommodations must be requested before you begin your registration.

If you need to confirm your accommodations have been applied to your registration, call:

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1-866-387-8602

Toll free for test takers in the United States, U.S. Territories (including American Samoa, Guam, Puerto Rico and the U.S. Virgin Islands) and Canada

Monday–Friday, 8:30 a.m.–5 p.m. ET

Yes. You may retake a Praxis test on a date that is at least 28 days after your most recent test date.

This applies even if you canceled your scores on a test taken previously. If you violate this restriction, the scores from your retest will be canceled by ETS and your test fees will not be refunded.

Rescheduling or Canceling a Test

Yes. If your test is available at home and you wish to reschedule to an at home appointment, you can do so for free. You have two options:

1. For immediate service, reschedule your test appointment through your Praxis account.
2. Contact Praxis customer support from Monday–Friday, 8 a.m.–6 p.m. ET, via phone at 1-800-772-9476. Due to increased demand on our customer support line, you may experience longer wait times.

Note: In either case, you must change your appointment at least three full days before your test date.

Test Environment and Equipment

Yes, if:

1. Your computer has at least Mac OS^® X 10.5. Note that it is recommended you use Mac OS X 10.13 High Sierra.
2. You are using a Chrome™ or Firefox^® browser.
3. The ETS Test Browser is installed.
4. It passes the ProctorU Equipment Check.

Test Preparation

• Gather the materials you'll need for your test session.
  • Passport or other acceptable ID
  • Acceptable note-taking materials, such as a whiteboard or plastic transparency sheet
  • Cellphone or hand-held mirror for check-in
• Remove all other items from the area.
• Make sure the area meets all environment requirements.

On Test Day

This video offers a closer look at how to prepare your testing area, the check-in process and what you should expect during your at home test. The check-in process takes approximately 20 minutes.

Yes. A human proctor during your entire test session. A human proctor will connect with you during the check-in process, verify your ID and monitor you throughout the entire session to ensure you are following testing procedures. The proctor assigned to monitor you could be male or female.

You will also be monitored by artificial intelligence (AI) technology to help ensure test security.

If you need to contact or chat with the proctor during your test, you should speak to get their attention or use the LogMeIn chat function. It may take 30–60 seconds for the proctor to reply.

If the proctor is attempting to chat with you, the chat icon (a blue owl) will bounce up and down.

Most tests don't include a break. However, you have the option to take a short, unscheduled restroom break if you're taking one of the following:

• Praxis^® Core Academic Skills for Educators combined test (5751 and 5752)
• Elementary Education: Multiple Subjects test (5001)
• Elementary Education: Three Subject Bundle—Mathematics, Social Studies and Science (5901)
• Pennsylvania Grades 4–8 Core Assessment (5152)
• Elementary Education: Content Knowledge for Teaching (7811)

If you choose to take a break, you must take it after the conclusion of one test, but before completing review of the General Directions for the next test. Your test clock won't start until you return and complete the General Directions.

See the policies associated with unscheduled breaks.

Troubleshooting Technical Issues

You must resolve all issues (shown in red) and pass the equipment check before checking in for your test. If you can't resolve the issues yourself, contact ProctorU using the contact form at the bottom of the equipment check page. Live Help Desk technicians are available to assist you.

Note: You must resolve all issues before your test appointment, or you won't be able to test.

• Run the ProctorU Equipment Check at the time of day you plan to test to make sure you don't have any bandwidth issues.
• Run a final equipment check shortly before your test session starts.
• Close all browsers and applications not needed for the test. This can help prevent bandwidth issues while you test.
• Make sure any other devices in your household that use the internet are not running.

For additional information and troubleshooting help, visit the ProctorU Test-taker Resource Page.

If you lose your internet connection momentarily, you'll automatically be reconnected to the proctor when your connection is restored. If your exam can be reopened, your proctor will do so for you.

If you can't reconnect and speak to the proctor via the LogMeIn chat function, call ProctorU at 1-855-772-8678 for assistance.

Scores

As with a test taken at a test center, you can send your scores to four agencies or institutions at no additional cost.

Please note: Automatic score reporting is not available in all states for at home testing. To see if your state offers it, see Automatic Reporting. If you want to make changes to your free score recipients, you may do so up until three days before your test date by logging in to your Praxis account.

See Sending Your Praxis Scores.

SPARK is a formally definedcomputerprogramming language based on the Ada programming language, intended for the development of high integrity software used in systems where predictable and highly reliable operation is essential. It facilitates the development of applications that demand safety, security, or business integrity.

Originally, there were three versions of the SPARK language (SPARK83, SPARK95, SPARK2005) based on Ada 83, Ada 95 and Ada 2005 respectively.

A fourth version of the SPARK language, SPARK 2014, based on Ada 2012, was released on April 30, 2014. SPARK 2014 is a complete re-design of the language and supporting verification tools.

The SPARK language consists of a well-defined subset of the Ada language that uses contracts to describe the specification of components in a form that is suitable for both static and dynamic verification.

In SPARK83/95/2005, the contracts are encoded in Ada comments and so are ignored by any standard Ada compiler, but are processed by the SPARK 'Examiner' and its associated tools.

SPARK 2014, in contrast, uses Ada 2012's built-in 'aspect' syntax to express contracts, bringing them into the core of the language. The main tool for SPARK 2014 (GNATprove) is based on the GNAT/GCC infrastructure, and re-uses almost the entirety of the GNAT Ada 2012 front-end.

Technical overview[edit]

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SPARK utilises the strengths of Ada while trying to eliminate all its potential ambiguities and insecure constructs. SPARK programs are by design meant to be unambiguous, and their behavior is required to be unaffected by the choice of Ada compiler. These goals are achieved partly by omitting some of Ada's more problematic features (such as unrestricted parallel tasking) and partly by introducing contracts which encode the application designer's intentions and requirements for certain components of a program.

The combination of these approaches allows SPARK to meet its design objectives, which are:

• logical soundness
• rigorous formal definition
• simple semantics
• security
• bounded resource (space and time) requirements.
• minimal runtime system requirements

Contract examples[edit]

Consider the Ada subprogram specification below:

In pure Ada this might increment the variable X by one or one thousand; or it might set some global counter to X and return the original value of the counter in X; or it might do absolutely nothing with X at all.

With SPARK 2014, contracts are added to the code to provide additional information regarding what a subprogram actually does. For example, we may alter the above specification to say:

This specifies that the Increment procedure does not use (neither update nor read) any global variable and that the only data item used in calculating the new value of X is X itself.

Alternatively, the designer might specify:

This specifies that Increment will use the global variable Count in the same package as Increment, that the exported value of Count depends on the imported values of Count and X, and that the exported value of X does not depend on any variables at all and it will be derived from constant data only.

If GNATprove is then run on the specification and corresponding body of a subprogram, it will analyse the body of the subprogram to build up a model of the information flow. This model is then compared against that which has been specified by the annotations and any discrepancies reported to the user.

These specifications can be further extended by asserting various properties that either need to hold when a subprogram is called (preconditions) or that will hold once execution of the subprogram has completed (postconditions). For example, we could say the following:

This, now, specifies not only that X is derived from itself alone, but also that before Increment is called X must be strictly less than the last possible value of its type and that afterwards X will be equal to the initial value of X plus one.

Verification conditions[edit]

GNATprove can also generate a set of verification conditions or VCs. These conditions are used to establish whether certain properties hold for a given subprogram. At a minimum, the GNATprove will generate VCs to establish that all run-time errors cannot occur within a subprogram, such as:

• array index out of range
• type range violation
• division by zero
• numerical overflow.

If a postcondition or any other assertion is added to a subprogram, GNATprove will also generate VCs that require the user to show that these properties hold for all possible paths through the subprogram.

Under the hood, GNATprove uses the Why3 intermediate language and VC Generator, and the CVC4, Z3, and Alt-Ergo theorem provers to discharge VCs. Use of other provers (including interactive proof checkers) is also possible through other components of the Why3 toolset.

History[edit]

The first version of SPARK (based on Ada 83) was produced at the University of Southampton (with UK Ministry of Defence sponsorship) by Bernard Carré and Trevor Jennings. Subsequently the language was progressively extended and refined, first by Program Validation Limited and then by Praxis Critical Systems Limited. In 2004, Praxis Critical Systems Limited changed its name to Praxis High Integrity Systems Limited. In January 2010, the company became Altran Praxis.

In early 2009, Praxis formed a partnership with AdaCore, and released 'SPARK Pro' under the terms of the GPL. This was followed in June 2009 by the SPARK GPL Edition 2009, aimed at the FOSS and academic communities.

In June 2010, Altran-Praxis announced that the SPARK programming language would be used in the software of US Lunar project CubeSat, expected to be completed in 2015.

In January 2013, Altran-Praxis changed its name to Altran.

The first Pro release of SPARK 2014 was announced on April 30, 2014, and was quickly followed by the SPARK 2014 GPL edition, aimed at the FLOSS and academic communities.

Industrial applications[edit]

Safety-related systems[edit]

SPARK has been used in several high profile safety-critical systems, covering commercial aviation (Rolls-Royce Trent series jet engines, the ARINC ACAMS system, the Lockheed Martin C130J), military aviation (EuroFighter Typhoon, Harrier GR9, AerMacchi M346), air-traffic management (UK NATS iFACTS system), rail (numerous signalling applications), medical (the LifeFlow ventricular assist device), and space applications (the Vermont Technical College CubeSat project).

Security-related systems[edit]

SPARK has also been used in secure systems development. Users include Rockwell Collins (Turnstile and SecureOne cross-domain solutions), the development of the original MULTOS CA, the NSA Tokeneer demonstrator, the secunet multi-level workstation, the Muen separation kernel and Genode block-device encrypter.

In August 2010, Rod Chapman, principal engineer of Altran Praxis, implemented Skein, one of candidates for SHA-3, in SPARK. In comparing the performance of the SPARK and C implementations and after careful optimization, he managed to have the SPARK version run only about 5 to 10% slower than C. Later improvement to the Ada middle-end in GCC (implemented by Eric Botcazou of AdaCore) closed the gap, with the SPARK code matching the C in performance exactly.^[1]

See also[edit]

Notes[edit]

1. ^Handy, Alex (August 24, 2010). 'Ada-derived Skein crypto shows SPARK'. SD Times. BZ Media LLC. Retrieved 2010-08-31.CS1 maint: discouraged parameter (link)

References[edit]

• John Barnes (2012). SPARK: The Proven Approach to High Integrity Software. Altran Praxis. ISBN978-0-9572905-1-8.
• John W. McCormick and Peter C. Chapin (2015). Building High Integrity Applications with SPARK 2014. Cambridge University Press. ISBN978-1-107-65684-0.
• Philip E. Ross (September 2005). 'The Exterminators'. IEEE Spectrum. 42 (9): 36–41. doi:10.1109/MSPEC.2005.1502527. ISSN0018-9235.

External links[edit]

Praxis Mac OS