Lecture 4 Problem Solving Search and Control Strategies

Lecture : 4 Problem Solving, Search and Control Strategies ﺣﻞ ﺍﻟﻤﺴﺎﺋﻞ ﻭﺍﻟﺒﺤﺚ ﻭﺍﺳﺘﺮﺍﺗﻴﺠﻴﺎﺕ ﺍﻟﺘﺤﻜﻢ 1 - Problem Solving 2 -Search and Control Strategies 3 -Exhaustive Searches 4 -Heuristic Search Techniques

What is problem solving, research and control strategies? Problem solving is fundamental element to many (AI) applications. ﺍﻻﺻﻄﻨﺎﻋﻲ ﻫﻮ ﻋﻨﺼﺮ ﺃﺴﺎﺳﻲ ﻟﻜﺜیﺮ ﻣﻦ ﺗﻄﺒیﻘﺎﺕ ﺍﻟﺬﻛﺎﺀ applications. There are two types of problems: 1 - The Problems like 2 - The real world problems Problem solving is : a process of generating solution from observed data. . ( ﻭﺣﻞ ﺍﻟﻤﺴﺎﺋﻞ ﻫﻮ ﺧﻄﻮﺍﺕ ﺇﻧﺘﺎﺝ ﺍﻟﺤﻠﻮﻝ ﻣﻦ ﺑیﺎﻧﺎﺕ ﻣﺸﺎﻫﺪﺓ )ﻣﻌﻄﺎﺓ

The problem is characterized by : ﻭﺗﺘﻤیﺰ ﺍﻟﻤﺴﺄﻠﺔ ﺏ ü a set of goals üa set of objects üa set of operations 1 - Problem Solving The field of problem solving is the main field when studying artificial intelligence. یﻌﺘﺒﺮ ﻣﺠﺎﻝ ﺣﻞ ﺍﻟﻤﺴﺎﺋﻞ ﻫﻮ ﺍﻟﻤﺠﺎﻝ ﺍﻟﺮﺋیﺴﻲ ﻋﻨﺪ ﺩﺭﺍﺳﺔ ﺍﻟﺬﻛﺎﺀ ﺍﻻﺻﻄﻨﺎﻋﻲ

Problem Definitions A Problem is defined by its elements and relationships. یﺘﻢ ﺗﻌﺮیﻒ ﺍﻟﻤﺴﺄﻠﺔ ﻋﻦ ﻃﺮیﻖ ﻋﻨﺎﺻﺮﻫﺎ ﻭﻋﻼﻗﺎﺗﻬﺎ To give a methodological definition, we need the following: 1 - Define a state space : that contains all the possible situations of problem objects, including impossible ones. ﺑﻤﺎ ، ﺍﻟﺬﻱ ﻳﺸﻤﻞ ﺟﻤﻴﻊ ﺍﻻﻭﺿﺎﻉ ﺍﻟﻤﻤﻜﻨﺔ ﻟﻜﺎﺋﻨﺎﺕ ﺍﻟﻤﺴﺄﻠﺔ : ﺗﻌﺮﻳﻒ ﻓﻀﺎﺀ ﺍﻟﺤﺎﻟﻪ . ﻓﻲ ﺫﻟﻚ ﺍﻻﻭﺿﺎﻉ ﺍﻟﻤﺴﺘﺤﻴﻠﺔ

2 -Search and Control Strategies (1) Search is a systematic test of a set of cases in order to know the path from the initial / root state to the target state. ﺍﻟﺒﺤﺚ ﻫﻮ ﺍﺧﺘﺒﺎﺭ ﻧﻈﺎﻣﻲ ﻟﻤﺠﻤﻮﻋﺔ ﺣﺎﻻﺕ ﻣﻦ ﺃﺠﻞ ﻣﻌﺮﻓﺔ ﺍﻟﻤﺴﺎﺭ ﻣﻦ ﺍﻟﺤﺎﻟﺔ . ﺍﻟﺠﺬﺭ ﺇﻟﻰ ﺍﻟﺤﺎﻟﺔ ﺍﻟﻬﺪﻑ / ﺍﻻﺑﺘﺪﺍﺋیﺔ üSearch tree The tree search is multi-level indexes used to drive search for data elements, according to certain search criteria. ﺷﺠﺮﺓ ﺍﻟﺒﺤﺚ ﻫﻲ ﻓﻬﺎﺭﺱ ﻣﺘﻌﺪﺩﺓ ﺍﻟﻤﺴﺘﻮیﺎﺕ ﻣﺴﺘﺨﺪﻣﺔ ﻟﻘیﺎﺩﺓ ﺍﻟﺒﺤﺚ ﻋﻦ

For example, point N, J in the following example

(2) Control Strategies The search control strategy is used to manage search operations , it includes the following types : ﻭﺗﺸﻤﻞ ﺍﻻﻧﻮﺍﻉ ، ﺍﺳﺘﺮﺍﺗﻴﺠﻴﺎﺕ ﺍﻟﺘﺤﻜﻢ ﺑﺎﻟﺒﺤﺚ ﺗﺴﺘﺨﺪﻡ ﻻﺩﺍﺭﺓ ﻋﻤﻠﻴﺎﺕ ﺍﻟﺒﺤﺚ : ﺍﻟﺘﺎﻟﻴﺔ 1 - Forward search 2 - Backward search 3 - Both forward and backward search 4 - Systematic search 5 - Heuristic search

(1) Forward search : ﺍﻟﺒﺤﺚ ﺍﻻﻣﺎﻣﻲ This strategy starts the search from the initial state towards the answer (target state ) This method is known as , data-directed. ﻭﺗﻌﺮﻑ ﻫﺬﻩ ﺍﻟﻄﺮﻳﻘﺔ ﺑﺎﻟﺘﻮﺟﻪ ﻧﺤﻮ. ﺗﺒﺪﺃ ﺑﺎﻟﺒﺤﺚ ﻣﻦ ﺍﻟﺤﺎﻟﺔ ﺍﻻﺑﺘﺪﺍﺋﻴﺔ ﺑﺎﺗﺠﺎﻩ ﺍﻟﻬﺪﻑ . ﺍﻟﺒﻴﺎﻧﺎﺕ (2) Backward search : ﺍﻟﺒﺤﺚ ﺍﻟﺨﻠﻔﻲ This strategy starts the search backwards from the target state (or end state) towards the initial state, or towards a partial solution of the problem. This method is known as, goal directed.

Breadth-first search tree

Depth-first search tree