optimizing_search_function

I used the first 30 and the last 10 books from the following book list as test data:
https://www.goodreads.com/list/show/1.Best_Books_Ever
After bug fixing, there are still 3 from the 40 books that cannot be found with abstract.
That is the current search success rate is 92.5% according to my insufficient test
======Details
Fixed Bugs:
Bug_1: Unexpected leading or trailing spaces 
Bug_2: Single quotation marks
e.g:
#The Hitchhiker's Guide to the Galaxy
#Charlotte's Web
#The Time Traveler's Wife 
#Ender's Game
#Alice's Adventures in Wonderland

Partly fixed Bugs:
Bug_3: Unsatisfaied Search Constraints
e.g:
(fixed)#(has no dbpprop:author)The Book Thief
#(not classified as Book)The Chronicles of Narnia
#(not classified as Book)Romeo and Juliet 
#(not classified as Book)Harry Potter and the Order of the Phoenix
If a book does not have rdf:type ontology:Book, I don't know how to recognize it.
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p.s. I just made a 'rake db:migrate' and didn't make any change in db/schema.rb manually.