Concept - Access Matrix

• Access matrix (s.12): subjects in rows, objects in columns, each entry lists the subject’s access rights to that object. Often sparse; can be decomposed by row or by column.
• The matrix can be decomposed by row or by column (s.12). The slide draws a capability list (per subject, s.13) and names ACLs in the summary (s.28). (Added context: column decomposition = ACL, per object, is the standard textbook mapping.)

	File 1	File 2	File 3
User A	Own, Read, Write		Own, Read, Write
User B	Read	Own, Read, Write
User C	Read, Write	Read	Read

(s.13; the slide’s capability list for A shows File 2 Read, which conflicts with the matrix, see the chunk note)

• Extended matrix (s.14-16): objects also include subjects (rights: control, owner), files, processes (wakeup, stop; delete), disk drives (seek, owner) and memory regions; * = copy flag.
• Devices (s.15): read/write, control operation (e.g. a disk seek), block/unblock. Memory: read/write regions, default no access. Subjects (s.16): ability to grant or delete rights of that subject to other objects.

Related: Concept - Copy Flag and Transfer Rules, Concept - Access Control Function, Concept - Access Control Elements. Appears in 04 Access Control - Chunk 01 (s.1-28).