A mutex lock is released immediately after entering a critical section. Group of answer choices True False

Answers

Answer 1

Answer:

False

Explanation:

The mutex lock should be purchased at the time when it would be entered in the critical section and it is released when it leaves the critical section

Also for improving out the critical resources synchronization among various processes, the mutex locks would be implemented

Therefore the given statement is false

Hence, the same is to be considered

Answer 2

Answer:

False

Explanation:

[tex] \: [/tex]

[tex] \: [/tex]


Related Questions

Question #4
Multiple Select
Which of the following statements are true regarding abstraction? Select 3 options.

O Creating a model must occur before abstraction.

O Refinement is the opposite of abstraction.

O Abstraction provides a way to see a complex situation more clearly.

O The level of abstraction needed depends on the situation and your goals.

O Abstraction is a process where details are added to further define the problem.

Answers

Answer:

B: the level of abstraction needed depends on the situation and your goals

C: refinement is the oppostie of abstraction

E: abstraction provides a way to see a complex situtation more clearly

Explanation:

I just completed the assignemnet and was checking it while I made this answer.

PLEASE HURRY!!!
Look at the image below!

Answers

Answer:

If the user enters 162.5, the output will be 162.5

Explanation:

Please click thanks button hun

A technology-literate knowledge worker: A. knows how and when to apply technology B. is a computer savvy worker C. knows all computer programming languages D. is knowledgeable about emerging technology

Answers

Answer:

A. knows how and when to apply technology

Explanation:

Technology can be defined as a branch of knowledge which typically involves the process of applying, creating and managing practical or scientific knowledge to solve problems and improve human life. Technologies are applied to many fields in the world such as medicine, information technology, cybersecurity, engineering, environmental etc.

A technology-literate knowledge worker knows how and when to apply technology. This ultimately implies that, someone who is well grounded or informed about a technology understands how and when to apply technology.

Basically, knowing how to use a technology simply means he or she understands the appropriate method or technique to be used in the application of a technology such as when solving a problem. Also, knowing when to use a technology means to know the appropriate time to use a particular technology without it having any repercussion or adverse effect.

Answer:

A

Explanation:

Think about it like this:

A literate person in writing doesn't just know letters, they know how to put them together. Now put that in terms of computers.

Data mining is an integral part of knowledge discovery in database (KDD), which is the overall process of converting ____ into _____. a. primary data / secondary data b. input data / output data c. raw data / useful information d. input data / data fusion

Answers

Answer:

c. raw data / useful information

Explanation:

Data mining can be described as the cat of converting raw data into useful information.

In simple terms it can be defined as the process of extracting usable data from a much larger set or data(raw). This is done through the use of various softwares that support the process.

Through data mining patterns, anomalies, correlations etc are found in the data which is then used in the prediction of likely outcomes.

(100 Points!)
The ___ search engine is the most common in use today.
A Boolean-based
B Crawler-based
C algorithm-based
D government-based

Answers

Answer:

B

Explanation

just did it on egd 2020

Answer:

Crawler-based

Explanation:

Just took the review

The Apple iPhone includes a settings menu where you can toggle various accessibility options on or off:
Bold Text
oo
Button Shapes
What is the minimum number of bits that can represent those 2 options?

Answers

The minimum amount of bits that can represent these two options is 2 bits.

The minimum amount of bits that can represent the two options is 2 bits.

What are accessibility options?

This is known to be the various accessibility features such as text-to-speech, etc. that can be found on any system or mobile phones.

Conclusively, there is the use of these features in a lot of technologies as it serves as  assistive technology. Note that lowest amount of bits that can represent these two options above is 2 bits as that is the only lowest point it can go.

Learn more about bits from

https://brainly.com/question/19667078

Question #3
Dropdown
What type of data is the result of each of the following lines of code?

str(2.34)
O float
O this causes an error
O int
O string

int('2')
O float
O this causes an error
O int
O string

float(2)
O float
O this causes an error
O int
O string

Answers

Answer:

string, int, float

Explanation:

just took it. have a good one!

Answer: string, int, float

Explanation: got it right on edgen

Has protection for proprietary software gone too far, as some critics suggest? (b) If not, why? (c) If so, what are the implications for innovation and competition in the computer industry? (d) How can we achieve an appropriate balance between those who hold legal rights to proprietary information and ordinary users who wish to access, share, and communicate that information? Defend your answer. Please elaborate (beyond a yes or no answer) and provide your "theoretical" rationale in support of your responses. (knowledge)

Answers

Answer:

In the clarification section following, the definition of the query is mentioned.

Explanation:

I acknowledge with maybe some opponents that patent security has gone too far. As tech manufacturers say, they already lost a lot of money in future sales in developed countries owing to software piracy. In reality, most consumers living in developed countries also couldn't manage to spend the rates set by certain tech firms, so firms did not lose any actual sales because, even in some developing countries, their pricey tech would essentially not sell mostly on the free market.So then, due to the extremely insufficient need for individuals, the consequences for creativity and competitiveness in the computing industry are restricted. Only the owners of copyright as well as the users with the resources to manage to offer for the pricey software have the opportunity to use it, as both a consequence of increasingly innovating, the market is restricted and weak.We ought to defined as the tendency doctrines: equal use as well as the first sale, to reach an acceptable compromise between someone who has legitimate rights to confidential information against common people who want to view, distribute, and interact the information. The first selling happens after the artist's concept has indeed been purchased out during the first occasion, during which stage the rightful owner loses ownership of the act's work.

In recent times, innovators including adversaries have focused on the use of reverse engineering, supported either by the reasonable-use doctrine of both the copyright Act.

Python uses sequencing to
A) allow the code to run faster
B) carryt out a series of steps
C) let the computer pick the order of the steps
D) make the code easier to read
plz help this is exammmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm

Answers

Answer:

B: Carry out a series of steps

Explanation:

Sequences is a general term for ordered sets. It tells in a set order what the program needs to do

PogChamp

Answer:

b

Explanation:

Which programming language hides the complexity of data objects and provides a simplified interface?
A.
machine language
B.
assembly language
C.
procedural language
D.
object-oriented language
E.
RAD

Answers

Answer:

D. Object-Oriented Langauge

Explanation:

Answer:

Your answer is D!

Explanation:

From PLATO!

Within the the Assignment05.java file, you must define the following static methods. In the main method, you may program any code that wish to test the methods you have been asked to define.
1) Write (define) a static method named displayGreeting, that takes no arguments and returns no value. When this function is called, it should print the text "Hello, and welcome!".
Example:
displayGreeting() will print Hello, and welcome!
2) Write (define) a static method named displayText, that takes a single String argument and returns no value. When this function is called, it should print the value of the argument that was passed to it.
Examples:
displayText("Hello") will print Hello
displayText("123") will print 123
displayText("abc" + "123") will print abc123
3) Write (define) a static method named printTotal, that takes three int arguments. When this function is called, it should print the sum of the three arguments passed to it. This function should return no value.
Examples:
printTotal(0, 0, 0) will print 0
printTotal(0, 1, 3) will print 4
printTotal(100, 23, 2) will print 125
4) Write (define) a static method named getTotal, that takes three int arguments. When this function is called, it should return the sum of the three arguments passed to it as an int.
Examples:
getTotal(0, 0, 0) will return 0
getTotal(0, 1, 3) will return 4
getTotal(100, 23, 2) will return 125
5) Write (define) a static method named getAverage, that takes three int arguments. When this function is called, it should return the average of the three arguments passed to it as a double.
Examples:
getAverage(0, 0, 0) will return 0.0
getAverage(0, 1, 3) will return 1.33333...
getAverage(100, 13, 7) will return 40.0
6) Write (define) a static method named averageLength, that takes three String arguments. When this function is called, it should return the average length (number of characters) of the String arguments passed to it as a double.
Examples:
averageLength("a", "abc", "ab") will return 2.0
averageLength("hello", "goodbye", "monday") will return 6.0
averageLength("wednesday", "tuesday", "monday") will return 7.33
7) Write (define) a static method named lengthOfShortest, that takes two String arguments. When this function is called, it should return the length (number of characters) of the shortest String argument passed to it as an int.
Examples:
lengthOfShortest("abc", "ab") will return 2
lengthOfShortest("hello", "goodbye") will return 5
lengthOfShortest("thursday", "friday") will return 6
8) Write (define) a static method named stringOfStars, that takes one String argument. When this function is called, it should return a String of asterisks (*) that is the same length as the string argument passed to it.
Examples:
stringOfStars("abc") will return "***"
stringOfStars("Hello, world!") will return "*************"
stringOfStars("0123456789") will return "**********"
9) Write (define) a static method named maxStringOfStars, that takes two String arguments. When this function is called, it should return a String of asterisks (*) that is the same length as the longest string argument passed to it.
Examples:
maxStringOfStars("a", "abc") will return "***"
maxStringOfStars("hello", "goodbye") will return "*******"
maxStringOfStars("thursday", "friday") will return "********"
10) Write (define) a static method named midStringOfStars, that takes three String arguments. When this function is called, it should return a String of asterisks (*) that is the same length as the string argument with the length that would be in the middle if the lengths of the arguments were arranged in ascending order.
Examples:
midStringOfStars("a", "abc", "ab") will return "**"
midStringOfStars("hello", "goodbye", "yes") will return "*****"
midStringOfStars("123456", "12", "1234") will return "****"

Answers

import java.util.Arrays;

public class Assignment05{

   public static void displayGreeting(){

       System.out.println("Hello, and welcome!");

   }

   public static void displayText(String txt){

       System.out.println(txt);

   }

   public static void printTotal(int a, int b, int c){

       System.out.println(a+b+c);

   }

   public static int getTotal(int a, int b, int c){

       return a+b+c;

   }

   public static double averageLength(String a, String b, String c){

       return (a.length() + b.length() + c.length())/3;

   }

   public static double getAverage(int a, int b, int c){

       return (a + b + c)/3;

   }

   public static int lengthOfShortest(String a, String b){

       if (a.length() > b.length()){

           return b.length();

       }

       else{

           return a.length();

       }

   }

   public static String stringOfStars(String txt){

       String newTxt = "";

       while (newTxt.length() < txt.length()){

           newTxt += "*";

       }

       return newTxt;

   }

   public static String maxStringOfStars(String txt, String txt1){

        String newTxt = "";

       if (txt.length() >= txt1.length()){

         

           while (newTxt.length() < txt.length()){

               newTxt += "*";

       }

           return newTxt;

       }

       else{

             while (newTxt.length() < txt1.length()){

           newTxt += "*";

       }

           return newTxt;

       }

   }

   public static String midStringOfStars(String a, String b, String c){

       String arr[] = {a, b, c};

       Arrays.sort(arr);

       String txt = "";

       while (txt.length() <  arr[1].length()){

           txt += "*";

       }

       return txt;

   }

   public static void main(String[] args){

       displayGreeting();

       displayText("hello");

       printTotal(1,2,3);

       System.out.println(getTotal(2,2,43));

       System.out.println(getAverage(100,13,7));

       System.out.println(averageLength("a", "abc", "ab"));

       System.out.println(lengthOfShortest("abc", "ab"));

       System.out.println(stringOfStars("abcd"));

       System.out.println(maxStringOfStars("a", "bbbbb"));

       System.out.println(midStringOfStars("aaa","aa", "abcedas"));

       

       

   }

}

I hope this helps!

Write a program that computes value of the following arithmetic expression for values of x and y entered by the user: 5.4xy - 12.3y 18.23x - 8.23

Answers

Answer:

Explanation:

The following code is written in Java and first asks the user to enter the values for X and Y, it then saves those values in two different variables and uses them in the arithmetic expression given in the question and solves it. The answer is saved to the variable named result and displayed on the window.

class brainly{

   public static void main(String[] args)

       {

           Scanner in = new Scanner(System.in);

           System.out.println("Enter value for x");

           double valueX = in.nextDouble();

           System.out.println("Enter value for y");

           double valueY = in.nextDouble();

           double result = (5.4 * valueX * valueY) - (12.3 * valueY * 18.23 * valueX) - 8.23;

           System.out.println(result);

       }

   }

8. Write a function that takes a 2D array as an input and outputs all values greater than 20 into a column array. Use logical indexing array

Answers

Answer:

Follows are the code to this question:

#include<stdio.h>//defining header file

int main()//defining main method

{

  int d[2][2];//defining 2D array

  int i, j;//defining integer variable

  printf("Enter values: \n");//print message

  for(i=0; i<2; i++)//defining for loop for input column value

  {

     for(j=0;j<2;j++)//defining for loop for input row value  

     {

        scanf("%d", &d[i][j]);//input values

     }

  }

  printf("value which is greater than 20: \n ");//print message

  for(i=0; i<2; i++)//defining for loop for print  column value  

  {

     for(j=0;j<2;j++)//defining for loop for print row value

     {

         if(d[i][j]>20)//defining if block that check value is greater then 20

         {

              printf("%d ", d[i][j]);//print values

         }

      }

     printf("\n");//use print for line break

  }

  return 0;

}

Output:

Enter values:  

44

12

11

55

value which is greater than 20:  

44  

55  

Explanation:

In the above-given code, a 2D array "d" and two integer variable "i and j" are defined, in which two for loop are used for input value from the user end.

After accepting the value from the user end, and again use the two for loop, in which, if block is defined, that checks array value is greater than 20 and print its values.

PLEASE HURRY!!!
Look at the image below!

Answers

The value of category will be normal because the if statement is false and the first elif statement is false but the second elif statement is true.

Doors and windows are important compositional elements that impact the facade of a building True False​

Answers

Answer:

true

Explanation:

Which type of evidence should victims collect to help officials catch cyber bullies ?

-home addresses
-birthdays
-social media
-usernames user
-passwords

Answers

Answer:

Social media

Explanation:

Social media and usernames user so that they can find them without any problem : D

Write the HTML code to make the text "Learn Magic" link to a page called "magic-tricks.html”.

Answers

Answer:

The answer to this question is given below in the explanation section.

Explanation:

The below code is written in HTML

************************************************************************************************

 <!DOCTYPE html>

<!--html start from here and this is comment line -->

<html lang="en-US">  

<body> <!--html body start from here -->

<!-- a link attribute is given below that links another file (magic-tricks)  in the same folder -->  

<p><a href="magic-tricks.html">Learn Magic</a></p>

</body><!--html body end at here -->

</html>

<!--html end at here and this is comment line -->

*************************************************************************************************

When you run this code, it is neccessary     for you to create another html file in same folder and named it "magic-tricks". When you will run the code into any browser and link "learn magic" will appear, as you will click on it "magic-tricks.html" file will get open.

     

A computer program checks to see if the user of a software program has clicked on a photo. This is an example of a requirement that can be evaluated in
a string statement.
a goto statement.
a global statement.
a conditional statement.

Answers

Answer:

A conditional statement

Explanation:

I just took the review and got it right

Answer:

A conditional statement

Explanation:

I took the test

Which type of programming language translates all lines of code together and then executes them at once?

Compiled
Interpreted
Machine
Python

Answers

Answer:

Compiled

Explanation:

Assistive Technologies: You have just purchased a new computer and, because of a visual impairment, you are having trouble reading the information on the screen. What are your next steps

Answers

Answer:

The definition has been mentioned below and according to the situation described.

Explanation:

If you already have recently purchased a new device and also have a visual disability condition, you increasing considering utilizing a few available assistive resources, such as screen readers, magnifiers, huge-print keyboards, as well as applications and resources for navigating assistance.  These resources are explicitly available for those instances often come pre-installed in a device window throughout today's context.

Lauren and her parents reviewed the lesson information on how to stay safe online. When Lauren told her parents that she had been using the password "Computer1” for all of her online accounts, her mother suggested that she change it.

Why did Lauren’s mother suggest she change her password?

It could be easily guessed.
It contained personal information.
It contained only one number.
It contained too many letters.

Answers

it could be easily guessed , the first one

Answer:

A): it could easily be guessed

Explanation:

I got it right thanks to the other person! give them brainiest, please!

Some systems automatically delete all user files when a user logs off or a job terminates, unless the user explicitly requests that they be kept. Other systems keep all files unless the user explicitly deletes them. Discuss the relative merits of each approach.

Answers

Answer:

Follows are the Scenario to this question:

Explanation:

Scenario 1:

Removing files trying to follow patient problems is effectively preserving a lot of bandwidth unless defined. Because the device doesn't allow unnecessary data to also be saved, and All system storage is also protected.

Its system efficiency also is increased as its device erases data which are not needed around the same time.

Scenario 2:

It is possible that its consumer unintentionally keeps forgetting to save information, and in that case, the user may lose a lot. Everything is therefore deleted before ensuring its customer.

Its machine may also be closed down due to varying any or even all model calibration, so that storage capacity helps to restore as the backup is still preserved.

Write a function password_check() that takes as input two strings newpassword and oldpassword, and accepts the new password (i.e., returns True) if newpassword is different from oldpassword and newpassword is at least 6 letters long. If the new password fails the check, your functions should return False

Answers

In python:

def password_check(newpassword, oldpassword):

   return True if newpassword != oldpassword and len(newpassword) >= 6 else False

Just for clarification, that return statement is on one line. I hope this helps!

4. What is the output of the following code snippet? void prevnext(int a, int& prv, int nxt) { prv = a - 1; nxt = a + 1; } int main() { int a = 100; int b = 0;

Answers

Answer:

Previous = 99, Next = 101

Explanation:

Given that a = 100

Previous says that it's formula is a - 1, where a = 100.

Therefore, previous code would show in its output as 100 - 1. 100 - 1 = 99.

Thus, the output of previous code will be 99

Like with previous, Next says that it's formula is a + 1, where a = 100.

Therefore, the next code would show in its output as 100 + 1. 100 + 1 = 101

Thus, the output of previous code will be 101

I hope that's explanatory enough. Thanks.

Please define identity theft

Answers

the action or crime of stealing.

Answer:

Identity theft is the deliberate use of someone else's identity, usually as a method to gain a financial advantage or obtain credit and other benefits in the other person's name, and perhaps to the other person's disadvantage or loss

Explanation:

Which arithmetic operation is used by a signed binary comparator to determine if two operands are equal

Answers

Answer:

Equality Operators

Explanation:

The equality operators, which are often written as "equal (==), and not-equal (!=)" are technically used by a signed binary comparator to determine if two operands are equal or not equal. They produce 1 in a situation where both operands have equal value, and 0 if they do not have equal value.

Hence, in this case, the correct answer is Equality Operators.

A computer provides each process with 65,536 bytes of physical address space divided into page-frames of 4096 bytes. A particular program has a text size of 32,768 bytes, a data size of 16,386 bytes, and a stack size of 15,870 bytes. Will this program fit in the address space?

Answers

Answer:

No, we require 17 pages but we have only 16 pages available

Explanation:

As computer provide allocated address space is 65,536 which is 2∧16 bytes and page size is 4096 bytes which is 2^12 bytes.

Therefore, the number that can be formed with each 4096 bytes are 16 pages (2^16 / 2^12 = 2^4).

That program text size is 32,768 bytes which is equal to 8 pages (32768/4096 = 8).

The data of the program require 16386 bytes which is equal to 5 pages (16386/4096 = 4.005) and the stack of that program require 4 pages (15870/4096 = 3.875).

Therefore, the program requires 17 pages but have only 16 pages that's why it doesn't fit in address space.

Hexadecimal representation of a code word CAB

Answers

Answer:

(434142)16

Explanation:

In Python
Write a constructor with parameters self, num_mins and num_messages. num_mins and num_messages should have a default value of 0.

Sample output with one plan created with input: 200 300, one plan created with no input, and one plan created with input: 500
My plan... Mins: 200 Messages: 300
Dad's plan... Mins: 0 Messages: 0
Mom's plan... Mins: 500 Messages: 0

Answers

class Messaging:

   txt = ""

   first = 0

   second = 0

   def __init__(self, num_mins=0, num_messages=0):

       self.txt = input("Who's plan is this? ")

       self.first = num_mins

       self.second = num_messages

   def print_Something(self):

       print(f"{self.txt} Mins: {self.first} Messages: {self.second}")

obj = Messaging(100, 100)

obj.print_Something()

If you want to change what's printed to the console, just manipulate the values in Messaging(). Leave them blank for 0.

Write a program that asks the user for a string of lowercase letters and numbers. The program should evaluate the string and report the number of vowels ('a', 'e', 'i', 'o', 'u') and numbers ('0', '1', '2', '3', '4', '5', '6', '7', '8', '9') in the string.

Answers

Answer:

Follows are the code to this question:

def vowel(x):#defining a method vowel that accept a parameter

   return(x=='a' or x=='e' or x=='i' or x=='o' or x=='u')#return char value

def number(x):#defining a method number that accept a parameter

   return(x=='0' or x=='1' or x=='2' or x=='3' or x=='4' or x=='5' or x=='6' or x=='7' or x=='8' or x=='9')#return number value

def main():#defining main method

   s=input("Enter a string: ")#defining string variable

   v=0#defining integer variable

   n=0#defining integer variable

   for f in s:#defining for loop for count value

       if vowel(f):#defining if to check vowel

           v=v+1#count vowel value

       elif number(f):#defining elif for count number

           n=n+1#count number value

   print("Total vowels: ",v)#print vowels value

   print("Total numbers: ",n)#print numbers value

main()

Output:

Enter a string: 678qeaft

Total vowels:  2

Total numbers:  3

Explanation:

In the above program code, three methods, "vowel, number and main" is defined, in which "vowel and number" accept an x variable in its parameter and return a value with their respective name.

Inside the main method a string variable "s" is defined that accepts a string value and defines an "n and v" integer variable, and in the for loop, it calls the above methods to use the integer variable to count string and number value and print its calculated value.

Other Questions
In the diagram, \angle ABD A B D and \angle BDC B D C are supplementary, the measure of \angle EDF=9x^\circ E D F = 9 x , and the measure of \angle ABD\:=\:\left(2x+105\right)^\circ. A B D = ( 2 x + 105 ) .Based on this information, which equation can be used to find the value of x? What are some needs and concerns that governments must consider when answering the Three BasicEconomic Questions? A hockey player needs to shoot a puck 55 meters from his current location to his opponent's goal to score a goal. After the shot, the puck is 120 centimeters from his opponent's goal. If there are 100 centimeters in 1 meter, how many meters did the puck travel? I need help with this What is the complementary DNA strand to the following DNA strand? *GAC T T TG ACTA AGCTa. GACTTTGACTAAGCTb. CTGAAACTGATTCGAC. GACUUUGACUAAGCUd. CTGAAACTGATACGA A population has a mean of 200 and a standard deviation of 50. Suppose a random sample of 100 people is selected from this population. What is the probability that the sample mean will be within /- 5 of the population mean The measures of two vertical angles are 58 and (3x + 4)". Find the value of x. Lorraine writes the equation shown. x squared + y minus 15 = 0 She wants to describe the equation using the term relation and the term function. The equation represents . Question 8Define and describe Basque language brainliest will be awarded The arrow on each of the spinners with be spun one time .which of the following shows all the possible outcome when each spinner is spun once . ASAP PLZ HELPA dolphin keeps up with a boat for a distance of 51 miles for 3 hours. What is the dolphins average speed? CAN SOMEONE HELP PLS !!! I really need the the help so can someone pls help mePart A: The sun produces 3.9 1033 ergs of radiant energy per second. How many ergs of radiant energy does the sun produce in 1.55 107 seconds? (5 points)Part B: Which is the more reasonable measurement of the diameter of a human hair:1.8 102 mm or 1.8 102 mm? Justify your answer. (5 points) Who has the authority to decide if a postmortem will be conducted if a client dies 2 hours after being admitted to the hospital URGENT HELP I'M DUMBif a store sells 4lb or apples for 6 dollars how much for money is it for 1lb of apples Solve the following inequality.2P - 3 > P + 6 How did the Hohokam and Anasazi people adapt to their physical environment?OA. They built networks of ditches to irrigate the desert.B. They cleared the rain forests to make room for farmland.OC. They built artificial islands in lakes.D. They created terraces to grow crops on mountainsides. Thirty-six students go on a field trip. The students are divided into groups of 7 students. How many groups of 7 will there be? Read this excerpt from "Rules of the Game."But I found it difficult to concentrate at home. My mother had a habit of standing over me while I plotted out my games. I think she thought of herself as my protective ally.What does this excerpt from "Rules of the Game" reveal about Waverly's mother's style of parenting?She is fun-loving and carefree.She is overbearing and controlling.She is excitable and anxious.She is quiet and thoughtful.ANSWER THIS AS FAST AS YOU CAN PLEASE! Which is not a reason the oval office is important and interesting to the public?A:The Oval Office reflects an unchanging style since President Roosevelt.B:Much of the president's most significant work id done in the Oval Office.C:The president has numerous important guests in the Oval Office, including world leaders.D:As a symbol of the president, the Oval Office serves an important role in American history.