Question: What is Winograd schema?
Evidence: A Winograd schema (Levesque, Davis, and Morgenstern 2012) is a pair of sentences, or of short texts, called the elements of the schema, that satisfy the following constraints:
The following is an example of a Winograd schema:
Here, the two sentences differ only in the last word: `large' vs. `small'. The ambiguous pronoun is `it'. The two antecedents are `trophy' and `brown suitcase'. A human reader will naturally interpret `it' as referring to the trophy in the first sentence and to the suitcase in the second sentence, using the world knowledge that a small object can fit in a large container, but a large object cannot fit in a small container (Davis 2013). Condition 4 is satisfied because either a trophy or a suitcase can be either large or small, and there is no reason to suppose that there would be a meaningful correlation of `small' or `large' with `trophy' or `suitcase' in a typical corpus.
We will say that an element of a Winograd schema is “solved” if the referent of the pronoun is identified.
An example of a pair of sentences satisfying conditions 1-3 but not 4 would be
Since women cannot be carcinogenic and pills cannot be pregnant, the pronoun `they' in these sentences is easily disambiguated using selectional restrictions. This pair is therefore not a valid Winograd schema.
The Winograd Schema Challenge (WSC) is a challenge for AI programs. The program is presented with a collection of sentences, each of which is one element of a Winograd schema, and is required to find the correct referent for the ambiguous pronoun. An AI program passes the challenge if its success rate is comparable to a human reader. The challenge is administered by commonsensereasoning.org and sponsored by Nuance Inc. It was offered for the first time at IJCAI-2016 (Morgenstern, Davis, and Ortiz, in preparation); the organizers plan to continue to offer it roughly once a year.
A Winograd schema (Levesque, Davis, and Morgenstern 2012) is a pair of sentences, or of short texts, called the elements of the schema, that satisfy the following constraints: 1. The two elements are identical, except for a single word or two or three consecutive words. 2. Each element contains a pronoun. There are at least two noun phrases in the element that, grammatically, could be the antecedents of this pronoun. However, a human reader will reliably choose one of these as plausible and reject the rest as implausible. Thus, for a human reader, the resolution of the pronoun in each element is unambiguous. 3. The correct resolution of the pronoun is different in the two sentences. 4. Computationally simple strategies, such as those based on single word associations in text corpora or selectional restrictions, will not suffice to disambiguate either element.  Rather, both disambiguation require some amount of world knowledge and of commonsense reasoning.
Answer: It is a pair of sentences, or of short texts, called the elements of the schema, that satisfy the following constraints: the two are identical, except for a single word or two or three consecutive words. Each element contains an unambiguous pronoun that has a different correct resolution. It has simple computing power.