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Topic: XOR


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  Exclusive or - Wikipedia, the free encyclopedia
Exclusive or (usual symbol XOR occasionally EOR), which is sometimes called exclusive disjunction, is a logical operator that results in true if one of the operands, but not both of them, is true.
The exclusive disjunction of propositions A and B is usually called A xor B, where "xor" stands for "exclusive or" and is pronounced "eks-or" or "zor".
(A xor B) ⇔ (A and not B) or (not A and B) ⇔ (A or B) and (not A or not B) ⇔ (A or B) and not (A and B)
en.wikipedia.org /wiki/Xor   (786 words)

  
 Xor swap algorithm - Encyclopedia.WorldSearch   (Site not responding. Last check: 2007-11-05)
In computer programming, the xor swap is an algorithm which uses the exclusive disjunction (XOR) operation to swap distinct values of variables having the same data type without using a temporary variable.
The following code in x86 assembly language uses the xor swap algorithm to swap the value in the AX register with the value in the BX register without using a temporary buffer.
In the XOR technique, the operands of all commands depend on the results of the previous command so they must be executed in strictly sequential order.
encyclopedia.worldsearch.com /xor_swap_algorithm.htm   (850 words)

  
 Got milk? Scientists discover key lactation gene
XOR was originally identified as encoding an enzyme involved in purine catabolism (the breakdown of adenine and guanine nucleotide bases).
To identify the function of XOR in the lactating mammary gland, Dr. Capecchi and colleagues generated mice lacking either one (heterozygous) or both (homozygous) functional copies of the XOR gene.
XOR is required for the envelopment of milk fat droplets with a phospholipid bilayer that is necessary for their secretion from the mammary epithelium.
www.eurekalert.org /pub_releases/2002-12/cshl-gms120902.php   (269 words)

  
 Simple XOR cipher - One Language   (Site not responding. Last check: 2007-11-05)
In cryptography, a simple XOR cipher is a relatively simple encryption algorithm that operates according to the principles:
Its primary merit is that it is simple to implement, and that the XOR operation is computationally inexpensive.
However, if the key is as long as the message (so it is never repeated) and its bits are random, it is in effect a one-time pad (also known as Vernam cipher), which is unbreakable in theory.
www.onelang.com /encyclopedia/index.php/Simple_XOR_cipher   (287 words)

  
 What is XOR encryption?
XOR encryption is a trivially simple symmetric cipher which is used in many applications where security is not a defined requirement.
The XOR operator is used to "flip" bits (zeroes and ones) in a piece of plaintext to create a ciphertext.
Understanding XOR and the other binary operators is a necessary step on the path to becoming a cryptologist.
www.tech-faq.com /xor-encryption.shtml   (314 words)

  
 Microsoft VBScript Operator: Xor   (Site not responding. Last check: 2007-11-05)
The Xor operator is used to perform a logical exclusion on two expressions, where the expressions are Null, or are of Boolean subtype and have a value of True or False.
The Xor operator can also be used a "bitwise operator" to make a bit-by-bit comparison of two integers.
In this example, the Xor performs a bitwise comparison on the 3 (in binary 011) and the 5 (in binary 101), and returns a 6 (in binary 110).
mikecaldwell.com /VBINDEX/xor.html   (96 words)

  
 [No title]   (Site not responding. Last check: 2007-11-05)
XOR, as part of a previous acquisition, at one time staffed nearly 100 tech professionals in the Windy City.
A spokesperson for XOR, which was founded in 1991 by (current Softbank satellite entrepreneur) Herb Morreale and acting CTO Trent Hein, would not comment on published queries indicating that Hein, along with CEO Greg Jacobsen and CFO Bob Komin, would be leaving the company.
Jacobsen, a former executive with MCI and EDS who joined XOR in the late 90s as part of a corporate recap effort, will also be moving on, according to sources close to the situation.
www.eprairie.com /printer/article.asp?newsletterID=2550   (281 words)

  
 PHP: gmp_xor - Manual
To be unbreakable XOR encryption must have a key that is totally random and is never re-used.
Although I am not an expert on cryptography, I understand that decyphering involves recognizing patterns and that it would be possible to decrypt code that was encoded using XOR with the same key if there were enough samples to examine.
XOR encryption only works if the key is at liest the same size as the plaintext, and the key is perfectly random.
www.php.net /manual/en/function.gmp-xor.php   (344 words)

  
 Cprogramming.com - Articles - XOR Encryption
XOR is a binary operator (meaning that it takes two arguments - similar to the addition sign, for example).
For example, if you XOR two variables of unknown values, you cannot tell from the output what the values of those variables are.
For example, if you take the operation A XOR B, and it returns TRUE, you cannot know whether A is FALSE and B is TRUE, or whether B is FALSE and A is TRUE.
www.cprogramming.com /tutorial/xor.html   (583 words)

  
 xor
xor cx,cx gibi kullanilmasi da hos bir kullanimidir.
hele xor çýktýsý ile d-flipflop çýktýsý arasýna and ve/veya nand baðlarsak, "abi bu high idi low oldu aman dikkat" (ya da tam tersi) çýktý üretir.
sonuc olarak boylelikle birlesme ozelligine apayri bir boyut kazandirir xor.
sozluk.sourtimes.org /show.asp?t=xor   (689 words)

  
 Igloo3D - XOR encryption of text
The XOR method of encryption makes things particularly easy as the same routine used to encrypt the data is also used to decrypt the data.
XOR encryption relies on a 'key', supplied by either the program, or user.
The beautiful thing about this method means that if I now XOR the result with the key (100110) again, we will end up with the original number.
www.angelfire.com /mo3/pengwin/devtut1.html   (295 words)

  
 Computer Technology Review: Xor Support In The Disk Drives - RAID systems, part 2 - Technology Tutorial - Tutorial
XOR the old data from the data drive with the old parity data from the parity drive.
XOR the new data with the parity data and write the result to the parity drive.
The solution to this problem is moving the responsibility of calculating XOR data from the RAID controller to the disk drives instead.
www.findarticles.com /p/articles/mi_m0BRZ/is_3_20/ai_61620918   (1404 words)

  
 XOR : Java Glossary   (Site not responding. Last check: 2007-11-05)
Further, the generated byte code for the xor version will be more compact, and the generated machine code will execute more quickly.
The idea was if a diskette was scratched destroying a circular track, or scratched radially, or if a big buttery thumbprint destroyed a blob of the disk, it was still recoverable because the data were recorded redundantly.
If a sector were destroyed, you would XOR together the remaining 10 sectors to reconstruct the missing sector.
mindprod.com /jgloss/xor.html   (567 words)

  
 Regulation of xanthine oxidoreductase by intracellular iron -- Martelin et al. 283 (6): C1722 -- AJP - Cell Physiology
In considerations of the pathophysiological role of XOR in vivo, its tissue expression is crucial.
The XOR protein and activity levels were determined 17 h after the transfection (lanes 1 and 2; bars 1 and 2) and after a further 24 h of incubation with normal medium (lanes 3 and 4; bars 3 and 4) or 100 µM DFO (lanes 5 and 6; bars 5 and 6).
The mechanism of the increase in XOR mRNA caused by DFO was not studied further and remains unclear.
ajpcell.physiology.org /cgi/content/full/283/6/C1722   (4114 words)

  
 Definition of XOR
Exclusive disjunction (usual symbol xor) is a logical operator that results in true if one of the operands (not both) is true.
In digital logic design, a two-input xor logic gate is often thought of as a programmable inverter, in that if one input is held at a logic '1', the output will be the inverse of the other input.
The xor operation is a more complex logical function than 'or' and 'and'.
www.wordiq.com /definition/XOR   (685 words)

  
 XOR chairman now its CEO   (Site not responding. Last check: 2007-11-05)
XOR has worked with more than 1,400 clients, including Cisco Systems and Sun Microsystems Inc. The electronic-business services industry that XOR competes in is projected to grow to $290 billion by 2004, according to International Data Corp.
In 1991, XOR was founded as an e-business development and information technology infrastructure company by University of Colorado graduates Trent Hein and Herb Morreale.
In February, XOR co-founder Morreale said in a lawsuit he filed against XOR in Boulder County District Court that the company faced "inadequate cash flow," and didn't uphold an agreement to buy back some of his unvested stock shares worth about $675,000.
www.broomfieldenterprise.com /business/12bxor.html   (500 words)

  
 Logic Circuit - Example 1   (Site not responding. Last check: 2007-11-05)
Remember that an XOR gate's output (labeled C) is set to 1 if EITHER inputs (labeled A and B) are set to 1, except when both A and B are 1.
So, the XOR gate responds almost exactly like the OR gate, except that it produces a zero output when BOTH inputs are 1.
In conclusion, the XOR produces a 1 when exactly one of the inputs is 1, in all other case it produces a zero.
www.cs.odu.edu /~jbollen/CS149/gates/XOR.html   (603 words)

  
 AAAI Proceedings Template   (Site not responding. Last check: 2007-11-05)
The “Fuzzy XOR” function was calculated by the formula xor = ((p and not q) or (q and not p)) where “p and q” = min(p,q),  “p or q” = max(p,q), and “not p” = 1-p.
The “Polynomial XOR” function was calculated by using the same inputs as the neural network and using a Hilbert Curve Degree = 3.
Interestingly, the  “Fuzzy XOR” is fractal in appearance and yet remains close to a smooth curve and perhaps Taylor’s Theorem is not the lower bound of practicality for polynomials.
user890956.wx10.registeredsite.com /aaai2000.htm   (2297 words)

  
 Binary XOR Operation   (Site not responding. Last check: 2007-11-05)
The binary XOR operation (also known as the binary XOR function) will always produce a 1 output if either of its inputs is 1 and will produce a 0 output if both of its inputs are 0 or 1.
In XCSB the binary XOR operator works in the same way, operating in parallel on sets of inputs and outputs within a variable or constant.
If we assign the value 0x24 to the variable J, which is the hexadecimal equivalent of the binary value 00100100, the value 0x21 to the variable K which is the hexadecimal equivalent of the binary value 00100001 and then perform the XCSB XOR operation on J and K and assign the result to M.
www.xcprod.com /titan/XCSB-DOC/binary_xor.html   (315 words)

  
 Journal of Vision - Visual XOR tasks are hard for monkeys, by Anderson, Peissig, & Sheinberg
We used a visual exclusive-or (XOR) task to probe the processes that support the abilities of monkeys to learn to recognize large numbers of individuals within an object class.
All three monkeys were able to eventually master a visual XOR object classification task, demonstrating that macaque monkeys can solve visual classification tasks requiring the use of conjunctions.
The discrepancy between performance on typical tasks and the XOR tasks challenges the assumption that feature conjunctions are a typical component of a monkey's approach to the usual laboratory visual object classification task.
www.journalofvision.org /4/8/731   (323 words)

  
 Xor - Maze puzzle game   (Site not responding. Last check: 2007-11-05)
Xor is an excellent adventure game with different mazes (levels), to practise spatial insight and logic.
The game Xor is created by Paul Carruthers and Ian Downend for the Atari ST and Amiga.
The first game 'Dots and Waves' is not representative for the XOR puzzles in the other games.
www.rvvz.demon.nl /xor   (285 words)

  
 XOR Gates   (Site not responding. Last check: 2007-11-05)
The XOR GATE is a similar to an OR gate except for the instance when all the inputs are high.
With the XOR gate when all the inputs are high the output will be low.
An example of the use of a XOR gate is in the half-adder circuit.
www.hcc.hawaii.edu:8000 /~richardi/113/c113_1c/1c_6/1c6.htm   (131 words)

  
 91072101.HTM   (Site not responding. Last check: 2007-11-05)
A data-dependent XOR is one where > the value that you XOR with depends on the data being encrypted.
A > data-independent XOR is one where the value that you XOR with does not > depend on this data.
I have shown that (to use your vocable) there is a data dependant XOR that will achieve the same result as the braid or the shuffle.
www.ciphersbyritter.com /BRAID/91072101.HTM   (445 words)

  
 The Magic of XOR
However, if you believe that XOR is associative (which it is), it's merely an extension of the first definition of XOR.
Thus, XOR applied to a bunch of Boolean variables is the same as summing up all the variables' values (where true is 1 and false is 0), and dividing mod 2.
is the XOR of all 10 bytes i
www.cs.umd.edu /class/spring2003/cmsc311/Notes/BitOp/xor.html   (1235 words)

  
 Key based Xor encryption explanation
Well because of the way xor gates work they have a very useful property, if I take an unknown input and xor it with a known value twice the output is the same as my origional unkown input.
This has the advantage that I can then tell them openly what the result of the xor is. As long as the second input remains secret no one else knows what the value I told him represents.
The strength of the encryption is decided by how "random" the squance of keys is. If the maths done on the key between each letter is simple then there will be a pattern in the generated keys and it becomes possible to predict the keys and crack the message.
www.andya.org.uk /jsplay/codeworks.html   (795 words)

  
 XOR - The Ultimate Maze Challenge   (Site not responding. Last check: 2007-11-05)
There are no random events in XOR's labyrinthine palace, and there is no premium on hand-eye coordination.
You have all the time in the world to work out the precise nature of the hazards you encounter.
Logical thinking, strategy and tactical problem solving are part of the XOR experience.
xor.ovine.net   (105 words)

  
 CertiGuide to A+ (A+ 4 Real) - Error Correcting Code (ECC) and XOR
XOR calculates the RAID-5 parity for data and can be used reconstructing corrupted or missing data.
XOR parity calculations are more intensive than simpler parity calculations, and as a result have a significant impact on host system performance.
RAID-5, which uses XOR parity, should only be implemented on a controller that uses hardware-based XOR through its own processor or coprocessor to han-dle the calculations instead of utilizing the host CPU.
certiguide.com /apfr/cg_apfr_ErrorCorrectingCodeECCandXOR.htm   (410 words)

  
 Truth Tables and Logic   (Site not responding. Last check: 2007-11-05)
The XOR rule can be used to test bits for equality.
XOR is combined with AND for use in addition.
XOR detects if the inputs are equal or not.
www.softwareforeducation.com /sms32v50_manual/380-TruthTables.htm   (476 words)

  
 Deriving the XOR Function
On the previous page we stated that the Exclusive-OR, or XOR function can be described verbally as, "Either A or B, but not both." In the realm of digital logic there are several ways of stating this in a more detailed and precise format.
While this illustrates a practical application using all three of the basic gate types, it is cumbersome to construct on a printed circuit board.
There are commercial packages which contain four XOR gates, but often only a single XOR function is wanted in a given application.
www.play-hookey.com /digital/xor_function.html   (415 words)

  
 PHY107 Other Logic Gates
For a two-input XOR the output is similar to that from the OR gate except it is 0 when both inputs are 1.
In general, an XOR gate gives an output value of 1 when there are an odd number of 1's on the inputs to the gate.
Therefore an equivalent circuit would comprise an XOR gate, the output of which feeds into the input of a NOT gate.
www.shef.ac.uk /uni/academic/N-Q/phys/teaching/phy107/othergates.html   (462 words)

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