| (4 intermediate revisions by 3 users not shown) | |||
| Line 8: | Line 8: | ||
---- | ---- | ||
| − | I am having trouble with exercise 2.4.10. I don't understand how I can prove what is being asked without using a specific range or function. | + | I am having trouble with exercise 2.4.10. I don't understand how I can prove what is being asked without using a specific range or function. Can anyone help with this? |
| + | |||
| + | ''' Prof. Alekseenko: ''' Perhaps one could start from looking at | ||
| + | functions <math> f(x)\,</math> and <math> g(y)\,</math> closely. | ||
| + | |||
| + | Here is a hint: consider any point <math> (x_0,y_0) \,</math>. | ||
| + | |||
| + | (1) What can be said about <math> f(x_{0})\,</math> and <math> h(x_0,y_0) \,</math>? | ||
| + | |||
| + | |||
| + | |||
| + | (2) Similarly, what can be said about <math> g(y_{0})\,</math> and <math> h(x_0,y_0)\,</math>? | ||
| + | |||
| + | |||
| + | (3) Finally, what can be said about <math> f(x_0)\,</math> | ||
| + | and <math> g(y_0)\, </math> for any <math>x_0\in X </math> and <math>y_0 \in Y</math>? | ||
| + | |||
| + | |||
| + | (4) How can this help to establish the desired inequality? | ||
| + | |||
| + | |||
| + | Can anybody fill in the detail? | ||
| + | |||
| + | |||
| + | '''Reply from a Student:''' So Here's my rough draft of it. I think this is enough but I could be missing something. Could not figure out how to get this looking good for the wiki so I used an image upload site. here's the link. http://imgur.com/Ae0sJ.jpg | ||
| + | |||
| + | |||
| + | '''Prof. Alekseenko:''' Thanks very much! The solution seems ok. A few minor detail can be corrected, but overall I do not see any problems with the proof. The last step, however, needs to be justified using the appropriate theorem in this section. | ||
Latest revision as of 08:39, 10 February 2010
To ask a new question, add a line and type in your question. You can use LaTeX to type math. Here is a link to a short LaTeX tutorial.
To answer a question, open the page for editing and start typing below the question...
go back to the Discussion Page
I am having trouble with exercise 2.4.10. I don't understand how I can prove what is being asked without using a specific range or function. Can anyone help with this?
Prof. Alekseenko: Perhaps one could start from looking at functions $ f(x)\, $ and $ g(y)\, $ closely.
Here is a hint: consider any point $ (x_0,y_0) \, $.
(1) What can be said about $ f(x_{0})\, $ and $ h(x_0,y_0) \, $?
(2) Similarly, what can be said about $ g(y_{0})\, $ and $ h(x_0,y_0)\, $?
(3) Finally, what can be said about $ f(x_0)\, $
and $ g(y_0)\, $ for any $ x_0\in X $ and $ y_0 \in Y $?
(4) How can this help to establish the desired inequality?
Can anybody fill in the detail?
Reply from a Student: So Here's my rough draft of it. I think this is enough but I could be missing something. Could not figure out how to get this looking good for the wiki so I used an image upload site. here's the link. 
Prof. Alekseenko: Thanks very much! The solution seems ok. A few minor detail can be corrected, but overall I do not see any problems with the proof. The last step, however, needs to be justified using the appropriate theorem in this section.
