XML Schema 1.1: Check subsumption relationship of complex type particles

In XML Schema 1.1 [1], the sequences of sub-elements allowed by a complex type is determined by its content model, a particle [2]. When one complex type restricts a base type, its particle is required to accept less [3] than that of the base type. When <all> model groups [4] are used in the restriction type (while the base type may also have an <all> group or have a combination of <sequence>s and <choice>s), the "accept less" requirement becomes an interesting task. The student is expected to study this problem, research existing solutions to similar issues (e.g. those listed here [5]), and propose and implement a solution. This work also helps to address the Priority Feedback [6] in the specification regarding the usefulness and implementation difficulty of this feature.

Possible Mentors: Sandy Gao

[1] http://www.w3.org/TR/xmlschema11-1/
[2] http://www.w3.org/TR/xmlschema11-1/#cParticles
[3] http://www.w3.org/TR/xmlschema11-1/#cos-content-act-restrict
[4] http://www.w3.org/TR/xmlschema11-1/#Model_Groups
[5] http://www.w3.org/TR/xmlschema11-1/#subsumptionCheckP
[6] http://www.w3.org/TR/xmlschema11-1/#derivation-ok-restriction