diff --git a/app/models/recommender_system.rb b/app/models/recommender_system.rb
index ff18563..e1fd047 100644
--- a/app/models/recommender_system.rb
+++ b/app/models/recommender_system.rb
@@ -376,7 +376,7 @@ def self.TF(word,text)
 
   # Inverse Document Frequency (IDF)
   def self.IDF(word)
-    Math::log(EuropeanaRS::Application::config.repository_total_entries/(1+(EuropeanaRS::Application::config.words[word] || 0)).to_f)
+    Math::log((2+EuropeanaRS::Application::config.repository_total_entries)/(1+(EuropeanaRS::Application::config.words[word] || 0)).to_f)
   end
 
   # TF-IDF
diff --git a/config/database.yml.example b/config/database.yml.example
index a6b8428..3589f54 100644
--- a/config/database.yml.example
+++ b/config/database.yml.example
@@ -2,6 +2,7 @@ development:
   adapter: postgresql
   encoding: unicode
   database: europeanars_development
+  host: localhost
   pool: 5
   username: username
   password: password
diff --git a/config/initializers/recommender_system.rb b/config/initializers/recommender_system.rb
index 367d1b9..015f404 100644
--- a/config/initializers/recommender_system.rb
+++ b/config/initializers/recommender_system.rb
@@ -79,7 +79,11 @@
 
   #Settings for speed up TF-IDF calculations
   config.max_text_length = (config.settings[:max_text_length].is_a?(Numeric) ? config.settings[:max_text_length] : 50)
-  config.repository_total_entries = [Lo.count,1].max
+  if ActiveRecord::Base.connection.table_exists?('los')
+    config.repository_total_entries = [Lo.count,1].max
+  else
+    config.repository_total_entries = 1
+  end
   
   #Keep words in the configuration
   words = {}
diff --git a/config/initializers/settings.rb b/config/initializers/settings.rb
index c727f61..1a8773b 100644
--- a/config/initializers/settings.rb
+++ b/config/initializers/settings.rb
@@ -3,5 +3,5 @@
 # Config accesible in EuropeanaRS::Application::config
 
 Rails.application.configure do
-  config.demo_user_available = (Rails.env==="development" and !User.where(:name => "Demo", :email => "demo@europeanars.com").first.nil?)
+  config.demo_user_available = (Rails.env==="development" and ActiveRecord::Base.connection.table_exists?('users') and !User.where(:name => "Demo", :email => "demo@europeanars.com").first.nil?)
 end
\ No newline at end of file