Past exam of the mathematics course of the University of Cambridge / 2006 / ia / Paper 5 / 2 / b / Solution Created 2026-09-24 Updated 2026-10-14
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False. An access matrix is an authorization table, not a numerical matrix representing a linear transformation. Its entries are sets of rights, such as permission to read or write an object. “Inverting” its organization means obtaining subject-oriented capability lists from object-oriented access control lists, or conversely, by enumerating and regrouping entries. Numerical floating-point matrix inversion has neither the relevant operations nor the relevant semantics, and many access tables are not even square.
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