In the field of Sentiment Analysis, another interesting (and problematic) linguistic structure is Conditionals.
Conditional sentences are tricky to analyze for sentiment detection because, even though they may contain positive or negative expressions, they do not express any sentiment. How is this possible? Well, let’s see an example: consider the sentence "If you want to buy a cheap Nexus just tell me".
Although the adjective "cheap" is in a predicative structure with respect to the noun "Nexus", it does not express any real sentiment about the phone model, since it is part of a conditional sentence (introduced by the subordinate conjunction "if"). Semantically, these conditional sentences express hypothetical facts or events which may or may not exist in reality. Therefore, in most of the cases, the sentiment value of them is neutral. Notice the contrast if we slighthly change the sentence and remove the conditional part: “I want to buy this cheap Nexus". In this case, the speaker voiced a positive opinion and a purchasing intent with no conditions attached.
Deep Linguistic Analysis allows for the correct identification of constituent and sentence boundaries and, therefore, it can classify different type of sentences, like conditionals, and treat them according to their real meaning.
See an example of a conditional sentence analyzed by Bitext's Natural Language engine: