## http 404 errorThe origin server did not find a current representation for the target resource or is not willing to disclose that one exists

I am new to spring mvc and I have done have everything proper seeing a tutorial.But still I am facing Http 404 error -The origin server did not find a current representation for the target resource or is not willing to disclose that one exists.why is that so?

I’m using IntelliJ IDE and tomcat server to run my code. under WEB-INF/ I have all dispatcher-servlet,jsp,web.xml file.

this is the controller class. I tried both the methods(/hello and /hi) but I’m not able to get successful results. @Controller

public class HelloController {     @RequestMapping("/hello")          public String printHello(ModelMap model) {         model.addAttribute("message", "Hello Spring MVC Framework!");         return "hello";     }     @RequestMapping("/hi")         public ModelAndView hiworld(){         ModelAndView modelAndView=new ModelAndView("hello");         modelAndView.addObject("message","hi bro its ok");         return modelAndView;     } } 

this the dispatcher-servlet.xml.

<bean class = "org.springframework.web.servlet.view.InternalResourceViewResolver">     <property name = "prefix" value = "/WEB-INF/" />     <property name = "suffix" value = ".jsp" /> </bean> 

this is my web.xml file Spring MVC Application

<servlet>     <servlet-name>dispatcher</servlet-name>     <servlet-class>         org.springframework.web.servlet.DispatcherServlet     </servlet-class>     <load-on-startup>1</load-on-startup> </servlet>  <servlet-mapping>     <servlet-name>dispatcher</servlet-name>     <url-pattern>/</url-pattern> </servlet-mapping> 

In hello.jsp file, I am printing the message

## Prove that there exists a machine which decides an infinite subset of halting problem

We already know that $H:=\{\langle M,w\rangle | M$ halts on $w\}$ is undecidable, then how can there possibly be a machine that decides any infinite subset of $H$ ?

## Checks whether a value exists in a dictionay

required_keys = [‘user_name’, ‘password’, ‘first_name’, ‘last_name​’, ’email’, ‘phone_number’, ‘is_admin​’, ‘date_registered’]

    for key in required_keys:         if not data[key]:             return False 

Let $$A$$ be a bounded operator on a Hilbert space $$H$$ with two invariant subspaces $$M$$ and $$N$$ s.t. $$N \subset M$$, dim$$(M \cap N^{\perp})> 1$$, and have no invariant subspaces between $$N$$ and $$M$$. Then, show that, there exists an operator $$B$$ on $$H$$ which has no proper invariant subspace.
All I want a hint for constructing $$B$$ with the help of $$A$$ and given conditions, even a little hint will be appreciated. Thanks in advance.
Let X be a normed space over the complex numbers and let $$T:X\to \mathbb{C}$$ be a linear map. Show that $$T$$ is a continuous map $$\iff$$ there is a subset $$A \subseteq X$$ where $$A$$ is non-empty and open and $$T(A) \neq \mathbb{C}$$.