Multiple use of Fermat's Principle , or Simple, Finite Tessellation (Unfolding)

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First consider a specific question. Given a triangle and two interior points, a person at Point-1 is required to 'touch' all the 3 sides of the triangle exactly once and return to Point-2. Find the minimum possible distance he/she needs to travel to accomplish the given condition. Certainly, this is easily solved if one knows concepts like Fermat's Principle, Polygon Tessellation, etc. But it takes 12 (i.e. 2*n!, n=3) operations to find such path. (Basically, we Tessellate the figure to fit in a straight line across multiple images).



enter image description here



More General Question : Given an n-sided polygon and two interior points find such shortest distance. Clearly, this is easily found in 2*n! steps, i.e. O(n!). We see this isn't that efficient algorithm. Plus I have noticed that in total there are only n distinct path-lengths available for a polygon with n-sides.



More General Question : Consider closed, connected curve made up of several small curves (instead of straight line-segments as in above) and two interior points. Find such shortest distance traveled by a Person at Point-1 who touches all 'individual' small curves and returns to Point-2. (This is pretty unsolved for general cases - certainly we use the concept of reflection of light...but I don't know how complex this can go!)



I am interested in something faster than this (Tessellation/Multiple-Reflections which is taking O(n!) time) algorithm (for the polygonal problem). Please suggest improvements/different algorithms if you are aware of such a problem.







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    First consider a specific question. Given a triangle and two interior points, a person at Point-1 is required to 'touch' all the 3 sides of the triangle exactly once and return to Point-2. Find the minimum possible distance he/she needs to travel to accomplish the given condition. Certainly, this is easily solved if one knows concepts like Fermat's Principle, Polygon Tessellation, etc. But it takes 12 (i.e. 2*n!, n=3) operations to find such path. (Basically, we Tessellate the figure to fit in a straight line across multiple images).



    enter image description here



    More General Question : Given an n-sided polygon and two interior points find such shortest distance. Clearly, this is easily found in 2*n! steps, i.e. O(n!). We see this isn't that efficient algorithm. Plus I have noticed that in total there are only n distinct path-lengths available for a polygon with n-sides.



    More General Question : Consider closed, connected curve made up of several small curves (instead of straight line-segments as in above) and two interior points. Find such shortest distance traveled by a Person at Point-1 who touches all 'individual' small curves and returns to Point-2. (This is pretty unsolved for general cases - certainly we use the concept of reflection of light...but I don't know how complex this can go!)



    I am interested in something faster than this (Tessellation/Multiple-Reflections which is taking O(n!) time) algorithm (for the polygonal problem). Please suggest improvements/different algorithms if you are aware of such a problem.







    share|cite|improve this question























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      up vote
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      down vote

      favorite











      First consider a specific question. Given a triangle and two interior points, a person at Point-1 is required to 'touch' all the 3 sides of the triangle exactly once and return to Point-2. Find the minimum possible distance he/she needs to travel to accomplish the given condition. Certainly, this is easily solved if one knows concepts like Fermat's Principle, Polygon Tessellation, etc. But it takes 12 (i.e. 2*n!, n=3) operations to find such path. (Basically, we Tessellate the figure to fit in a straight line across multiple images).



      enter image description here



      More General Question : Given an n-sided polygon and two interior points find such shortest distance. Clearly, this is easily found in 2*n! steps, i.e. O(n!). We see this isn't that efficient algorithm. Plus I have noticed that in total there are only n distinct path-lengths available for a polygon with n-sides.



      More General Question : Consider closed, connected curve made up of several small curves (instead of straight line-segments as in above) and two interior points. Find such shortest distance traveled by a Person at Point-1 who touches all 'individual' small curves and returns to Point-2. (This is pretty unsolved for general cases - certainly we use the concept of reflection of light...but I don't know how complex this can go!)



      I am interested in something faster than this (Tessellation/Multiple-Reflections which is taking O(n!) time) algorithm (for the polygonal problem). Please suggest improvements/different algorithms if you are aware of such a problem.







      share|cite|improve this question













      First consider a specific question. Given a triangle and two interior points, a person at Point-1 is required to 'touch' all the 3 sides of the triangle exactly once and return to Point-2. Find the minimum possible distance he/she needs to travel to accomplish the given condition. Certainly, this is easily solved if one knows concepts like Fermat's Principle, Polygon Tessellation, etc. But it takes 12 (i.e. 2*n!, n=3) operations to find such path. (Basically, we Tessellate the figure to fit in a straight line across multiple images).



      enter image description here



      More General Question : Given an n-sided polygon and two interior points find such shortest distance. Clearly, this is easily found in 2*n! steps, i.e. O(n!). We see this isn't that efficient algorithm. Plus I have noticed that in total there are only n distinct path-lengths available for a polygon with n-sides.



      More General Question : Consider closed, connected curve made up of several small curves (instead of straight line-segments as in above) and two interior points. Find such shortest distance traveled by a Person at Point-1 who touches all 'individual' small curves and returns to Point-2. (This is pretty unsolved for general cases - certainly we use the concept of reflection of light...but I don't know how complex this can go!)



      I am interested in something faster than this (Tessellation/Multiple-Reflections which is taking O(n!) time) algorithm (for the polygonal problem). Please suggest improvements/different algorithms if you are aware of such a problem.









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      edited Jul 22 at 13:37
























      asked Jul 22 at 13:32









      Amit Bendkhale

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