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2. to cook or not to cook

Mary is a vegetarian.  She only cooks and eats vegetarian food.  John is carnivorous.  He cooks and eats meat!  If Mary wants to eat broccoli and cheese, she can learn how to cook broccoli and cheese.  If she wants corn of the cob, she can learn how to cook corn on the cob.  The same goes for John.  If he wants to eat greasy hamburger, he can learn how to cook greasy hamburger.  If he wants to eat fatty hotdog, he can learn how to cook fatty hotdog.  Every time John and Mary want to eat something new, they can learn how to cook it.  This requires that John and Mary to each have a very big head in order to learn all the recipes.

But wait, there are people out there called chefs!  These are very special kinds of chefs catering only to vegetarians and carnivores.  These chefs only know how to cook two dishes: one vegetarian dish and one meat dish.  All John and Mary have to do is to know how to ask such a chef to cook their favorite dish.  Mary will only order the vegetarian dish, while John will only order the meat dish!

How do we model the vegetarian, the carnivore, the chef, the two kinds of dishes the chef cooks, and how the customer orders the appropriate kind of dish from the chef?

The food

To simplify the problem, let's treat food as String.  (In a more sophisticated setting, we may want to model food as some interface with veggie and meat as sub-interface.)

The food consumers

Vegetarians and carnivores are basically the same animals.  They have the basic ingredients such as salt and pepper to cook food.  They differ in the kind of raw materials they stock to cook their foods and in the way they order food from a chef.  Vegetarians and Carnivores can provide the materials to cook but do not know how to cook!  In order to get any cooked meal, they have to ask a chef to cook for them. We model them as two concrete subclasses of an abstract class called AEater . AEater has two concrete methods, getSalt and getPepper , and an abstract method called order , as shown in the table below.

Top-level abstract definition
public abstract class AEater { public String getSalt() {return "salt"; }public String getPepper() { return "pepper";} /*** Orders n portions of appropriate food from restaurant r. */public abstract String order(IChef r, Integer n); // NO CODE BODY!}
Concrete implementations
public class Vegetarian extends AEater{ public String getBroccoli() {return "broccoli"; }public String getCorn() { return "corn";} public String order(IChef c, Object n) {// code to be discussed later; }} public class Carnivore extends AEater{ public String getMeat() {return "steak"; }public String getChicken() { return "cornish hen";} public String getDog() {return "polish sausage"; }public String order(IChef c, Object n) { // code to be discussed later;} }

The chef

The chef is represented as an interface IChef with two methods, one to cook a vegetarian dish and one to cook a meat dish, as shown in the table below.

Questions & Answers

how do you translate this in Algebraic Expressions
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Shanjida
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
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what's the easiest and fastest way to the synthesize AgNP?
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Cied
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I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
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Porter
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I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
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what is nano technology
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what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
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the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
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Source:  OpenStax, Principles of object-oriented programming. OpenStax CNX. May 10, 2013 Download for free at http://legacy.cnx.org/content/col10213/1.37
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