An Efficient Algorithm for Inference in Rough Set Flow Graphs

In this chapter, we review a graphical framework for reasoning from data, called rough set flow graphs (RSFGs), and point out issues of current interest involving RSFG inference. Our discussion begins by examining two methods for conducting inference in a RSFG. We highlight the fact that the order of variable elimination, called an elimination ordering, affects the amount of computation needed for inference. The culminating result is the incorporation of an algorithm for obtaining a good elimination ordering into our RSFG inference algorithm.

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An Efficient Algorithm for Finding Maximum Cycle Packings in Reducible Flow Graphs

Algorithmica ◽

10.1007/s00453-005-1174-x ◽

2005 ◽

Vol 44 (3) ◽

pp. 195-211 ◽

Cited By ~ 3

Author(s):

Xujin Chen ◽

Wenan Zang

Keyword(s):

Efficient Algorithm ◽

Flow Graphs

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On Time-sensitive Control Dependencies

ACM Transactions on Programming Languages and Systems ◽

10.1145/3486003 ◽

2022 ◽

Vol 44 (1) ◽

pp. 1-37

Author(s):

Martin Hecker ◽

Simon Bischof ◽

Gregor Snelting

Keyword(s):

Execution Time ◽

Efficient Algorithm ◽

Reactive Systems ◽

Efficient Algorithms ◽

Control Flow ◽

Efficient Computation ◽

Performance Measurements ◽

Flow Graphs

We present efficient algorithms for time-sensitive control dependencies (CDs). If statement y is time-sensitively control dependent on statement x , then x decides not only whether y is executed but also how many timesteps after x . If y is not standard control dependent on x , but time-sensitively control dependent, then y will always be executed after x , but the execution time between x and y varies. This allows us to discover, e.g., timing leaks in security-critical software. We systematically develop properties and algorithms for time-sensitive CDs, as well as for nontermination-sensitive CDs. These work not only for standard control flow graphs (CFGs) but also for CFGs lacking a unique exit node (e.g., reactive systems). We show that Cytron’s efficient algorithm for dominance frontiers [ 10 ] can be generalized to allow efficient computation not just of classical CDs but also of time-sensitive and nontermination-sensitive CDs. We then use time-sensitive CDs and time-sensitive slicing to discover cache timing leaks in an AES implementation. Performance measurements demonstrate scalability of the approach.

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