## Dynamic Search-Space Pruning Techniques in Path Sensitization

### BibTeX

@MISC{_dynamicsearch-space,

author = {},

title = {Dynamic Search-Space Pruning Techniques in Path Sensitization},

year = {}

}

### OpenURL

### Abstract

Abstract — A powerful combinational path sensitization engine is required for the efficient implementation of tools for test pattern generation, timing analysis, and delay fault testing. Path sensitization can be posed as a search, in the n-dimensional Boolean space, for a consistent assignment of logic values to the circuit nodes which also satisfies a given condition. In this paper we propose and demonstrate the effectiveness of several new techniques for search-space pruning for test pattern generation. In particular, we present linear-time algorithms for dynamically identifying unique sensitization points and for dynamically maintaining reduced head line sets. In addition, we present two powerful mechanisms that drastically reduce the number of backtracks: failure-driven assertions and dependency-directed backtracking. Both mechanisms can be viewed as a form of learning while searching and have analogs in other application domains. These search pruning methods have been implemented in a generic path sensitization engine called LEAP. A test pattern generator, TG-LEAP, that uses this engine was also developed. We present experimental results that compare the effectiveness of our proposed search pruning strategies to those of PODEM, FAN, and SOCRATES. In particular, we show that LEAP is very efficient in identifying undetectable faults and in generating tests for difficult faults. I.

### Citations

259 |
Forward Reasoning and Dependency-Directed Backtracking in a System for Computer-Aided Circuit Analysis
- Stallman, Sussman
- 1977
(Show Context)
Citation Context ...ur dependency-backtracking algorithm has linear time complexity and introduces negligible overhead if no backtracking is required. Dependency-directed backtracking schemes were originally proposed in =-=[19]-=- in an application of artificial intelligence techniques to circuit analysis. The above search-space pruning techniques have been incorporated in a path sensitization engine called LEAP (LEveldependen... |

236 | An implicit enumeration algorithm to generate tests for combinational logic
- Goel
- 1981
(Show Context)
Citation Context ...ed as a form of learning while searching [3]. We also introduce an algorithm to perform dependency-directed backtracking. In most algorithms for path sensitization such as the D-algorithm [14], PODEM =-=[7]-=-, FAN [5], TOPS [8], SOCRATES [15] and EST [6], the search process always backtracks to the previous node in the decision tree, i.e. it performs chronological backtracking. In some situations, however... |

155 | On the acceleration of test generation algorithms
- Fujiwara, Shimono
- 1983
(Show Context)
Citation Context ...d on a dynamic analysis of the search process, and present experimental data that demonstrate their power for test pattern generation. We start by illustrating how dynamic unique sensitization points =-=[5]-=- can be identified in linear time; in contrast the algorithm suggested in SOCRATES [16] has worst-case quadratic time complexity. Next, we show that the notion of head lines can This work was supporte... |

109 |
Diagnosis of automata failures: A calculus and a method
- Roth
- 1966
(Show Context)
Citation Context ... can be viewed as a form of learning while searching [3]. We also introduce an algorithm to perform dependency-directed backtracking. In most algorithms for path sensitization such as the D-algorithm =-=[14]-=-, PODEM [7], FAN [5], TOPS [8], SOCRATES [15] and EST [6], the search process always backtracks to the previous node in the decision tree, i.e. it performs chronological backtracking. In some situatio... |

109 |
Sarfert “SOCRATES: A Highly Efficient Automatic Test Pattern Generation System
- Schulz, Trischler, et al.
- 1987
(Show Context)
Citation Context ...arching [3]. We also introduce an algorithm to perform dependency-directed backtracking. In most algorithms for path sensitization such as the D-algorithm [14], PODEM [7], FAN [5], TOPS [8], SOCRATES =-=[15]-=- and EST [6], the search process always backtracks to the previous node in the decision tree, i.e. it performs chronological backtracking. In some situations, however, the search process can provably ... |

73 |
A Topological Search Algorithm for ATPG
- Kirkland, Mercer
- 1987
(Show Context)
Citation Context ...rning while searching [3]. We also introduce an algorithm to perform dependency-directed backtracking. In most algorithms for path sensitization such as the D-algorithm [14], PODEM [7], FAN [5], TOPS =-=[8]-=-, SOCRATES [15] and EST [6], the search process always backtracks to the previous node in the decision tree, i.e. it performs chronological backtracking. In some situations, however, the search proces... |

53 |
Finding dominators in a directed graphs
- Tarjan
- 1974
(Show Context)
Citation Context ... referred to as a unique sensitization implication (USI). The identification of static USPs was proposed in FAN, TOPS, and SOCRATES as a pre-processing step and was based on the concept of dominators =-=[20]-=-. It is possible, however, for dynamic USPs to emerge as the search process evolves; such UPSs cannot be identified with pre-processing techniques. A second version of SOCRATES [16] finds dynamic USPs... |

46 |
Improved Deterministic Test Pattern Generation with Applications to Redundancy Identification
- Schultz, Auth
- 1989
(Show Context)
Citation Context ...nstrate their power for test pattern generation. We start by illustrating how dynamic unique sensitization points [5] can be identified in linear time; in contrast the algorithm suggested in SOCRATES =-=[16]-=- has worst-case quadratic time complexity. Next, we show that the notion of head lines can This work was supported in part by the NSF under grant MIP-9014058 and in part by the Portuguese JNICT under ... |

31 | Learning while searching in constraint-satisfactionproblems
- Dechter
- 1986
(Show Context)
Citation Context ...thod for identifying nodes that must assume certain values to eliminate these inconsistencies. This is referred to as failure-driven assertions and can be viewed as a form of learning while searching =-=[3]-=-. We also introduce an algorithm to perform dependency-directed backtracking. In most algorithms for path sensitization such as the D-algorithm [14], PODEM [7], FAN [5], TOPS [8], SOCRATES [15] and ES... |

25 |
Accelerated dynamic learning for test pattern generation in combinational circuits
- Kunz, Pradhan
- 1993
(Show Context)
Citation Context ...and [16] until phase DYN_1 [16], but without the implementation of instruction 2 of the unique sensitization procedure [15]. The results given for SOCRATES also use the improved learning criterion of =-=[10]-=-. Because our main goal is to compare the non-heuristic pruning techniques of each algorithm, only structural controllability/observability measures are used [1]. In TG-LEAP backtracing always stops a... |

24 |
An Effective Test Generation System for Sequential Circuits
- Marlett
- 1986
(Show Context)
Citation Context ...acking is linear. Because all relevant dependencies are determined, the dependency-directed scheme proposed is complete, in contrast with other schemes proposed for sequential test pattern generation =-=[11, 12]-=-. IV. RESULTS The techniques described in the previous section have been incorporated in a path sensitization algorithm, LEAP, implemented in C++, which forms the core of a test pattern generation sys... |

16 |
A Neutral List of 10 Combinational Benchmark Circuits and a Target Translator in FORTRAN
- Brglez, Fujiwara
- 1985
(Show Context)
Citation Context ...ndancy information of the circuit every time a fault is proved redundant, would eventually relate individual path sensitization problems. In the following, several tests are performed on the ISCAS’85 =-=[2]-=- benchmark suite, using a collapsed fault set for each circuit. For comparison purposes, all faults in each collapsed fault set are targeted. This option is intended to allow a thorough evaluation of ... |

10 |
Efficient and robust test generation-based timing analysis
- Silva, Sakallah
- 2003
(Show Context)
Citation Context ...g techniques have been incorporated in a path sensitization engine called LEAP (LEveldependent Analysis in Path sensitization). LEAP has been used to implement a combinational timing analyzer, TALEAP =-=[18]-=- as well as a test pattern generation system, TGLEAP which can also run customized versions of PODEM, FAN, and SOCRATES. In the next section we introduce the basic concepts required to implement failu... |

8 |
EST: The new frontier in automatic test-pattern generation
- Giraldi, Bushnell
- 1990
(Show Context)
Citation Context ...how. Future work is mainly intended to overcome this problem and to improve the inconsistency processing schemes proposed in LEAP. A natural evolution consists in introducing search state equivalence =-=[6]-=- and dominance [4] relations to further prune the search space. Actually, search state equivalence relations provide a complementary scheme with respect to dependencydirected backtracking; search stat... |

8 |
A Sequential Circuit Test Generation System
- Mallela, Wu
- 1985
(Show Context)
Citation Context ...acking is linear. Because all relevant dependencies are determined, the dependency-directed scheme proposed is complete, in contrast with other schemes proposed for sequential test pattern generation =-=[11, 12]-=-. IV. RESULTS The techniques described in the previous section have been incorporated in a path sensitization algorithm, LEAP, implemented in C++, which forms the core of a test pattern generation sys... |

8 |
A Method to Calculate Necessary Assignments
- Rajski, Cox
- 1990
(Show Context)
Citation Context ...t and detectable. In a complete test pattern generation system, fault simulation would be employed to reduce the test set size, and to randomly detect some difficult detectable faults, as proposed in =-=[13]-=-, [15] and [21]. We further note thatsCircuit R: redundant D: detectable C432 (R) 259gat s-a-1 C432 (R) 347gat s-a-1 C1908 (R) 565 s-a-1 C2670 (R) 2282 s-a-1 C2670 (R) 2417 s-a-1 C7552 (D) 3695 s-a-1 ... |

6 |
An Efficient Test Generation Algorithm Based on Search Space Dominance
- Fujino, Fujiwara
- 1992
(Show Context)
Citation Context ...s mainly intended to overcome this problem and to improve the inconsistency processing schemes proposed in LEAP. A natural evolution consists in introducing search state equivalence [6] and dominance =-=[4]-=- relations to further prune the search space. Actually, search state equivalence relations provide a complementary scheme with respect to dependencydirected backtracking; search state equivalence rela... |

5 |
Adaptive Backtrace and Dynamic Partitioning Enhance APTG
- Lioy
- 1988
(Show Context)
Citation Context ... can be derived. We note that whenever an unjustified vertex x i becomes a new head line, x i also becomes justified. In [17], dynamic head lines are further extended by using topological don’t cares =-=[9]-=-. x 7 x 8 x 10 707 decision level implication level ( 70 , ) x1 = 0 ( 5, i) x2 = 0 ( 71 , ) x3 = 1 ( 2, j) x6 = 1 ( 72 , ) x4 = 1 ( 72 , ) x5 = 1 C. Failure-Driven Assertions ( 73 , ) x7 = 1 ( 74 , ) ... |

3 |
Search-Space Pruning Heuristics for Path Sensitization in Test Pattern Generation
- Silva, Sakallah
- 1993
(Show Context)
Citation Context ...merging head lines into new head lines is repeated until no more new head lines can be derived. We note that whenever an unjustified vertex x i becomes a new head line, x i also becomes justified. In =-=[17]-=-, dynamic head lines are further extended by using topological don’t cares [9]. x 7 x 8 x 10 707 decision level implication level ( 70 , ) x1 = 0 ( 5, i) x2 = 0 ( 71 , ) x3 = 1 ( 2, j) x6 = 1 ( 72 , )... |