1 / 10

Homework 0

Homework 0. You may work in groups of one, two or three. Due on 18 of jan at beginning of class. Find a problem, and discuss how you would go about making it into a search problem (as in the water-jug example, or the tangram example below).

levia
Download Presentation

Homework 0

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Homework 0 • You may work in groups of one, two or three. • Due on 18 of jan at beginning of class. • Find a problem, and discuss how you would go about making it into a search problem (as in the water-jug example, or the tangram example below). • In particular, what is the initial state, the goal state, the operators. Does the search tree have any special properties? How would that effect your choice of search algorithm… • I imagine this taking 1 to 3 pages of text, and some high quality drawings. • You must do a unique problem! Register your idea on the sign up sheet outside my door.

  2. The Tangram Problem Informal Problem Description: Given these 7 shapes, assemble them into a square.

  3. Note that the goal state here is implicit. We can describe it, but we cannot actually draw it out. In general, we don’t know if there is a goal state. As it happens, in this case there is 1 (not counting rotations and reflections). goal state solution At a low level, how do we know if the shapes make up the goal state?

  4. The initial state is a “blank” square. We know the size of the square (we can simply sum the areas of the seven shapes)

  5. What should the operators be? How about insert(shape_number,x,y,r) ? Bad idea, operators must be atomic… • We can use an insertion function that requires: • At least one edge of the shape must touch an edge of another shape or the walls of the box. • At least one vertex of the shape must coincide with a vertex of another shape or of the box.

  6. … … …

  7. An idea to reduce the branching factor. Since like the 8-queens problem, the order in which the shapes are inserted does not matter (unlike the 8-puzzle or FWDC) we could randomly label the shapes 1 to 7 and only attempt to insert the ith shape at the ith level 2 3 1 5 7 4 6

  8. An BAD idea to reduce the branching factor! Since like the 8-queens problem, the order in which the shapes are inserted does not matter (true for humans, but not for search with the operators I defined) we could randomly label the shapes 1 to 7 and only attempt to insert the ith shape at the ith level Assume this labeling 1 3 2 5 7 4 6 No solution!

  9. An good idea to reduce the branching factor. If both 6 and 7 (or 3 and 5) are still available to be inserted, only consider inserting one of them. 2 3 1 5 7 4 6

  10. … • What can we say about the search tree? • It is exactly depth 7 • Every node at depth 7 is a solution. • How does this effect the choice of search algorithm? … …

More Related