| | |
induction
Please support our Computer Science advertiser: Learn about neural networks and artificial intelligence.
![]() |
•
•
•
•
Originally Posted by SNA
can anyone please explain me in simple words about induction and how to use induction to prove something.
This can be divided into a set of sub-propositions:
"The sum of the first 1 odd numbers equals 1*1."
"The sum of the first 2 odd numbers equals 2*2"
"The sum of the first 3 odd numbers equals 3*3."
and so on.
Just for the sake of syntax, let's let P(N) represent the proposition, "The sum of the first N odd numbers equals N*N." I.e.
P(1) = "The sum of the first 1 odd numbers equals 1*1."
P(2) = "The sum of the first 2 odd numbers equals 2*2."
P(3) = "The sum of the first 3 odd numbers equals 3*3."
and so on. Each of these are 'propositions', remember, which can be proven either true or false.
Proof by induction is in two parts:
Step 1. Show that your "base case" proposition is true. That is, show that P(1) is true.
Step 2. Take some value M. Show that if the proposition P(M) is true, then the proposition P(M+1) is true.
Let's do this for the above example. First, we follow step 1, which means we need to show that P(1), the statement, "The sum of the first 1 odd numbers equals 1*1," is true. This is pretty trivial: clearly, 1 = 1*1. This completes step 1.
Then we perform step 2. To show that, for any value of M, if P(M) is true, then P(M+1) is true, it suffices to assume that P(M) is true, and then, based on this assumption, prove that P(M+1) is true.
Assume that P(M) is true, for some value of M. This means that the sum of the first M odd numbers equals M*M. That is,
1 + 3 + 5 + ... + (2M - 1) = M*M.
It follows that
1 + 3 + 5 + ... + (2M - 1) + (2M + 1) = M*M + 2M + 1
I.e. after factoring:
1 + 3 + 5 + ... + (2M - 1) + (2(M+1) - 1) = (M + 1)*(M + 1)
The left side of this equation is the sum of the first M+1 odd numbers, and the right side is (M+1)*(M+1). Hence, the statement, "The sum of the first M+1 odd numbers equals (M+1)*(M+1)," is true.
What does this tell us?
From step 1, we know that P(1) is true. From step 2, we know that if P(1) is true, then P(2) is true. Hence, P(2) is true. Then from step 2, we know that if P(2) is true, then P(3) is true. Hence, P(3) is true. And so on and so on, we can show that P(N) is true for any value of N.
All my posts may be redistributed under the GNU Free Documentation License.
![]() |
Similar Threads
- 'Object variable or With block variable not set' Error (ASP.NET)
- Help with student induction timetable database (Database Design)
- router problem (Networking Hardware Configuration)
- Question about binary tree & heaps (Computer Science)
- Calculating theta of a function (Computer Science)
- Page hangs or displays connection pooling max size error (ASP.NET)
Other Threads in the Computer Science Forum
- Previous Thread: [Schudling OS]Priority Level
- Next Thread: software design questions
| Thread Tools | Search this Thread |
Tag cloud for Computer Science
ai algorithm algorithms amazon assignment assignmenthelp assignments automata battery bigbrother binary bittorrent bizarre bletchleypark blogging bomb business cern codebreaker compiler computer computers computerscience computertrackingsoftware conversion csc data dataanalysis dataintepretation development dfa dissertation dissertations dissertationthesis dissertationtopic ebook employment energy extensions floatingpoint foreclosuresoftware fuel gadgets geeks givemetehcodez government graphics hardware history homeowners homeworkassignment homeworkhelp humor ibm idea ideas internet iphone ipod itcontracts jobs kindle laser laws lsmeans mainframes marketing mining mobileapplication msaccess netbeans networking news os p2p piracy piratebay programming research sas science security sex simulation software spying sql study supercomputer supercomputing sweden technology textfield turing turingtest two'scompliment uk virus warehouse ww2






