Algorithms for solving NP problems

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The purpose of presentation is to acquaint the listeners with the

The purpose of presentation is to acquaint the listeners with the

example of the problem of finding a Hamiltonian cycle in a graph and the «Knapsack problem»:
with the concept of «NP complexity problems»
with algorithms for solving these problems
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Cryptography is the art and science of protecting messages with encryption.

Cryptography is the art and science of protecting messages with encryption.
A

cryptographic algorithm (or cipher, or key) is a mathematical function or two mathematical related functions (one for encryption, the other for decryption).
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ALGORITHM RELIABILITY Unconditional reliability - recovery of the plaintext or key

ALGORITHM RELIABILITY

Unconditional reliability - recovery of the plaintext or key is

impossible with any amount of cipher text received by the cryptanalyst.
The algorithm is reliable if it is cracked will cost more than the cost of encrypted data take longer than keeping the data private the amount of data required exceeds the amount of data encrypted with a key.
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COMPLEXITY THEORY «Information theory claims that almost all cryptographic algorithms can

COMPLEXITY THEORY

«Information theory claims that almost all cryptographic algorithms can be

broken. Complexity theory determines whether they can be hacked before the thermal death of the universe».
Bruce Schneier. Applied Cryptography. Protocols, Algorithms, and Source Code in C
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COMPLEXITY THEORY DEFINES AND CLASSIFIES complexity of algorithms the complexity of the tasks themselves

COMPLEXITY THEORY DEFINES AND CLASSIFIES


complexity of algorithms
the complexity of the tasks

themselves
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P VS NP PROBLEM

P VS NP PROBLEM

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PROPERTIES OF NP-HARD PROBLEMS: NP-hard problem cannot be solved by existing

PROPERTIES OF NP-HARD PROBLEMS:

NP-hard problem cannot be solved by existing algorithms;
if

a polynomial solution to any such problem is found, then all problems from the NP class will be quickly solvable.
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Picture 1 - Hamiltonian graph with a distinguished Hamiltonian cycle

Picture 1 - Hamiltonian graph with a distinguished Hamiltonian cycle

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Picture 2 - example of the knapsack problem

Picture 2 - example of the knapsack problem

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Picture 3 - brute force tree for solving the problem of

Picture 3 - brute force tree for solving the problem of

packing a backpack with 3 items
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TABLE 1 - CONDITION OF THE PROBLEM OF PACKING A BACKPACK

TABLE 1 - CONDITION OF THE PROBLEM OF PACKING A BACKPACK

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Picture 6 - coordinate system illustrating the implementation of the dynamic Objects Weight

Picture 6 - coordinate system illustrating the implementation of the dynamic


Objects

Weight