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James W. Youdas - One of the best experts on this subject based on the ideXlab platform.
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Responsiveness of 2 Procedures for Measurement of Temporal and Spatial Gait Parameters in Older Adults
PM & R : the journal of injury function and rehabilitation, 2010Co-Authors: James W. Youdas, Katherine B. Childs, Megan L. Mcneil, Amy C. Mueller, Christopher M. Quilter, John H. HollmanAbstract:Objective To determine the responsiveness of the GAITRite system and a Stopwatch-footfall count technique for measurement of walking speed, cadence, and stride length during comfortable and fast-paced walking. Design Criterion standard. Setting Research laboratory in a physical therapy education program. Participants Twenty-four healthy volunteers (13 men, 11 women; mean age 74.5 years) without lower extremity injury or history of falls. Interventions Participants walked across a GAITRite mat with embedded pressure sensors at their self-selected comfortable and fast walking speeds. Simultaneously, an examiner, using a Stopwatch, recorded the elapsed time necessary to cross the mat and counted the number of complete footfalls. Main Outcome Measure(s) Walking speed, cadence, and stride length were compared between the GAITRite system and the Stopwatch-footfall count technique for both comfortable and fast walking speeds. Responsiveness values for each procedure were described by the 95% minimal detectable change (MDC). Results During comfortable self-paced walking, MDC values for the Stopwatch-footfall count technique ranged from 10% to 65% greater than those obtained for the GAITRite system. During fast self-paced walking MDC values for the Stopwatch-footfall count technique ranged from 26% to 65% larger than those measured by the GAITRite system for the temporal and spatial gait performance parameters. Conclusions When measured by the GAITRite system, the 95% MDC values for temporal and spatial gait parameters of older community-dwelling adults were more responsive to change than those obtained by the Stopwatch-footfall technique. Clinicians should recognize that self-selected walking speed, cadence, and stride length when obtained by an instrumented walkway must be equal to or exceed 12.6 cm/s, 8.4 steps/min, or 7 cm, respectively, for the change to be considered real change and not from measurement error.
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agreement between the gaitrite walkway system and a Stopwatch footfall count method for measurement of temporal and spatial gait parameters
Archives of Physical Medicine and Rehabilitation, 2006Co-Authors: James W. Youdas, John H. Hollman, Monica J. Aalbers, Holly N. Ahrenholz, Rebecca A. Aten, Joseph J. CremersAbstract:Abstract Youdas JW, Hollman JH, Aalbers MJ, Ahrenholz HN, Aten RA, Cremers JJ. Agreement between the GAITRite walkway system and a Stopwatch–footfall count method for measurement of temporal and spatial gait parameters. Objective To determine the agreement for measurements of stride length, cadence, and walking speed obtained from the GAITRite system and the Stopwatch–footfall count technique. Design Criterion standard. Setting Research laboratory in a physical therapy education program. Participants Forty healthy volunteers (13 men, 27 women) without lower-extremity injury. Interventions Participants walked across a GAITRite mat with embedded pressure sensors at their self-selected walking speed. Simultaneously, an examiner used a Stopwatch to record the elapsed time necessary to cross the mat and counted the number of complete footfalls. Main Outcome Measures Walking speed, cadence, and stride-length measures were compared between the GAITRite system and the Stopwatch–footfall count technique. Results Correlation coefficients comparing both systems were .97 for walking speed, .75 for cadence, and .85 for stride length. Ninety-five percent of the time we would expect the between-methods differences to range between .09 and −.05m/s for walking speed, between −1.5 and −24.3 steps/min for cadence, and between .01 and .37m for stride length. Conclusions This study shows that the GAITRite and Stopwatch–footfall count methods lack clinically acceptable agreement for the measurements of cadence and stride length in a group of healthy volunteers walking at their self-selected speeds. Clinicians who require precise measurement of cadence and stride length should consider using the GAITRite system instead of the Stopwatch–footfall count technique.
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Agreement Between the GAITRite Walkway System and a Stopwatch–Footfall Count Method for Measurement of Temporal and Spatial Gait Parameters
Archives of physical medicine and rehabilitation, 2006Co-Authors: James W. Youdas, John H. Hollman, Monica J. Aalbers, Holly N. Ahrenholz, Rebecca A. Aten, Joseph J. CremersAbstract:Abstract Youdas JW, Hollman JH, Aalbers MJ, Ahrenholz HN, Aten RA, Cremers JJ. Agreement between the GAITRite walkway system and a Stopwatch–footfall count method for measurement of temporal and spatial gait parameters. Objective To determine the agreement for measurements of stride length, cadence, and walking speed obtained from the GAITRite system and the Stopwatch–footfall count technique. Design Criterion standard. Setting Research laboratory in a physical therapy education program. Participants Forty healthy volunteers (13 men, 27 women) without lower-extremity injury. Interventions Participants walked across a GAITRite mat with embedded pressure sensors at their self-selected walking speed. Simultaneously, an examiner used a Stopwatch to record the elapsed time necessary to cross the mat and counted the number of complete footfalls. Main Outcome Measures Walking speed, cadence, and stride-length measures were compared between the GAITRite system and the Stopwatch–footfall count technique. Results Correlation coefficients comparing both systems were .97 for walking speed, .75 for cadence, and .85 for stride length. Ninety-five percent of the time we would expect the between-methods differences to range between .09 and −.05m/s for walking speed, between −1.5 and −24.3 steps/min for cadence, and between .01 and .37m for stride length. Conclusions This study shows that the GAITRite and Stopwatch–footfall count methods lack clinically acceptable agreement for the measurements of cadence and stride length in a group of healthy volunteers walking at their self-selected speeds. Clinicians who require precise measurement of cadence and stride length should consider using the GAITRite system instead of the Stopwatch–footfall count technique.
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Measurements of temporal aspects of gait obtained with a multimemory Stopwatch in persons with gait impairments.
The Journal of orthopaedic and sports physical therapy, 2000Co-Authors: James W. Youdas, Angela L. Atwood, Michael O. Harris-love, Tricia L. Stiller, Kathleen S. Egan, Terry M. TherneauAbstract:Study Design Repeated measures of 14 temporal factors of gait obtained with a multimemory Stopwatch from a variety of subjects with locomotor impairments. Objectives To estimate the intratester and...
Joseph J. Cremers - One of the best experts on this subject based on the ideXlab platform.
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agreement between the gaitrite walkway system and a Stopwatch footfall count method for measurement of temporal and spatial gait parameters
Archives of Physical Medicine and Rehabilitation, 2006Co-Authors: James W. Youdas, John H. Hollman, Monica J. Aalbers, Holly N. Ahrenholz, Rebecca A. Aten, Joseph J. CremersAbstract:Abstract Youdas JW, Hollman JH, Aalbers MJ, Ahrenholz HN, Aten RA, Cremers JJ. Agreement between the GAITRite walkway system and a Stopwatch–footfall count method for measurement of temporal and spatial gait parameters. Objective To determine the agreement for measurements of stride length, cadence, and walking speed obtained from the GAITRite system and the Stopwatch–footfall count technique. Design Criterion standard. Setting Research laboratory in a physical therapy education program. Participants Forty healthy volunteers (13 men, 27 women) without lower-extremity injury. Interventions Participants walked across a GAITRite mat with embedded pressure sensors at their self-selected walking speed. Simultaneously, an examiner used a Stopwatch to record the elapsed time necessary to cross the mat and counted the number of complete footfalls. Main Outcome Measures Walking speed, cadence, and stride-length measures were compared between the GAITRite system and the Stopwatch–footfall count technique. Results Correlation coefficients comparing both systems were .97 for walking speed, .75 for cadence, and .85 for stride length. Ninety-five percent of the time we would expect the between-methods differences to range between .09 and −.05m/s for walking speed, between −1.5 and −24.3 steps/min for cadence, and between .01 and .37m for stride length. Conclusions This study shows that the GAITRite and Stopwatch–footfall count methods lack clinically acceptable agreement for the measurements of cadence and stride length in a group of healthy volunteers walking at their self-selected speeds. Clinicians who require precise measurement of cadence and stride length should consider using the GAITRite system instead of the Stopwatch–footfall count technique.
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Agreement Between the GAITRite Walkway System and a Stopwatch–Footfall Count Method for Measurement of Temporal and Spatial Gait Parameters
Archives of physical medicine and rehabilitation, 2006Co-Authors: James W. Youdas, John H. Hollman, Monica J. Aalbers, Holly N. Ahrenholz, Rebecca A. Aten, Joseph J. CremersAbstract:Abstract Youdas JW, Hollman JH, Aalbers MJ, Ahrenholz HN, Aten RA, Cremers JJ. Agreement between the GAITRite walkway system and a Stopwatch–footfall count method for measurement of temporal and spatial gait parameters. Objective To determine the agreement for measurements of stride length, cadence, and walking speed obtained from the GAITRite system and the Stopwatch–footfall count technique. Design Criterion standard. Setting Research laboratory in a physical therapy education program. Participants Forty healthy volunteers (13 men, 27 women) without lower-extremity injury. Interventions Participants walked across a GAITRite mat with embedded pressure sensors at their self-selected walking speed. Simultaneously, an examiner used a Stopwatch to record the elapsed time necessary to cross the mat and counted the number of complete footfalls. Main Outcome Measures Walking speed, cadence, and stride-length measures were compared between the GAITRite system and the Stopwatch–footfall count technique. Results Correlation coefficients comparing both systems were .97 for walking speed, .75 for cadence, and .85 for stride length. Ninety-five percent of the time we would expect the between-methods differences to range between .09 and −.05m/s for walking speed, between −1.5 and −24.3 steps/min for cadence, and between .01 and .37m for stride length. Conclusions This study shows that the GAITRite and Stopwatch–footfall count methods lack clinically acceptable agreement for the measurements of cadence and stride length in a group of healthy volunteers walking at their self-selected speeds. Clinicians who require precise measurement of cadence and stride length should consider using the GAITRite system instead of the Stopwatch–footfall count technique.
Louis-marie Traonouez - One of the best experts on this subject based on the ideXlab platform.
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Symbolic unfolding of parametric Stopwatch Petri nets
Formal Methods in System Design, 2013Co-Authors: Claude Jard, Didier Lime, Olivier H. Roux, Louis-marie TraonouezAbstract:We address the problem of unfolding safe parametric Stopwatch time Petri nets (PSwPNs), i.e., safe time Petri nets (TPNs) possibly extended with time parameters and Stopwatches. We extend the notion of branching process to account for the dates of the occurrences of events and thus define a symbolic unfolding for PSwPNs. In the case of TPNs we also propose a method based on our so-called time branching processes to compute a finite complete prefix of the symbolic unfolding. The originality of our work relies on a precise handling of direct conflicts between events, and the analysis of their effects on the constraints between the firing dates of those events.
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Symbolic Unfolding of Parametric Stopwatch Petri Nets
2010Co-Authors: Louis-marie Traonouez, Didier Lime, Claude Jard, Bartosz Grabiec, Olivier H. RouxAbstract:This paper proposes a new method to compute symbolic unfoldings for safe Stopwatch Petri Nets (SwPNs), extended with time parameters, that symbolically handle both the time and the parameters. We propose a concurrent semantics for (parametric) SwPNs in terms of timed processes à la Aura and Lilius. We then show how to compute a symbolic unfolding for such nets, as well as, for the subclass of safe time Petri nets, how to compute a finite complete prefix of this unfolding. Our contribution is threefold: unfolding in the presence of Stopwatches or parameters has never been addressed before. Also in the case of time Petri nets, the proposed unfolding has no duplication of transitions and does not require read arcs and as such its computation is more local. Finally the unfolding method is implemented (for time Petri nets) in the tool Romeo.
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TACAS - Romeo: A Parametric Model-Checker for Petri Nets with Stopwatches
Tools and Algorithms for the Construction and Analysis of Systems, 2009Co-Authors: Didier Lime, Olivier Roux, Charlotte Seidner, Louis-marie TraonouezAbstract:Last time we reported on Romeo, analyses with this tool were mostly based on translations to other tools. This new version provides an integrated TCTL model-checker and has gained in expressivity with the addition of parameters. Although there exists other tools to compute the state-space of Stopwatch models, Romeo is the first one that performs TCTL model-checking on Stopwatch models. Moreover, it is the first tool that performs TCTL model-checking on timed parametric models. Indeed, Romeo now features an efficient model-checking of time Petri nets using the Uppaal DBM Library, the model-checking of Stopwatch Petri nets and parametric Stopwatch Petri nets using the Parma Polyhedra Library and a graphical editor and simulator of these models. Furthermore, its audience has increased leading to several industrial contracts. This paper reports on these recent developments of Romeo.
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Parametric Model-Checking of Stopwatch Petri Nets
Journal of Universal Computer Science, 2009Co-Authors: Louis-marie Traonouez, Didier Lime, Olivier RouxAbstract:At the border between control and verification, parametric verification can be used to synthesize constraints on the parameters to ensure that a system verifies given specifications. In this paper we propose a new framework for the parametric verification of time Petri nets with Stopwatches. We first introduce a parametric exten- sion of time Petri nets with inhibitor arcs (ITPNs) with temporal parameters and we define a symbolic representation of the parametric state-space based on the classical state-class graph method. Then, we propose semi-algorithms for the parametric model- checking of a subset of parametric TCTL formulae on ITPNs. These results have been implemented in the tool Romeo and we illustrate them in a case-study based on a scheduling problem.
John H. Hollman - One of the best experts on this subject based on the ideXlab platform.
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Responsiveness of 2 Procedures for Measurement of Temporal and Spatial Gait Parameters in Older Adults
PM & R : the journal of injury function and rehabilitation, 2010Co-Authors: James W. Youdas, Katherine B. Childs, Megan L. Mcneil, Amy C. Mueller, Christopher M. Quilter, John H. HollmanAbstract:Objective To determine the responsiveness of the GAITRite system and a Stopwatch-footfall count technique for measurement of walking speed, cadence, and stride length during comfortable and fast-paced walking. Design Criterion standard. Setting Research laboratory in a physical therapy education program. Participants Twenty-four healthy volunteers (13 men, 11 women; mean age 74.5 years) without lower extremity injury or history of falls. Interventions Participants walked across a GAITRite mat with embedded pressure sensors at their self-selected comfortable and fast walking speeds. Simultaneously, an examiner, using a Stopwatch, recorded the elapsed time necessary to cross the mat and counted the number of complete footfalls. Main Outcome Measure(s) Walking speed, cadence, and stride length were compared between the GAITRite system and the Stopwatch-footfall count technique for both comfortable and fast walking speeds. Responsiveness values for each procedure were described by the 95% minimal detectable change (MDC). Results During comfortable self-paced walking, MDC values for the Stopwatch-footfall count technique ranged from 10% to 65% greater than those obtained for the GAITRite system. During fast self-paced walking MDC values for the Stopwatch-footfall count technique ranged from 26% to 65% larger than those measured by the GAITRite system for the temporal and spatial gait performance parameters. Conclusions When measured by the GAITRite system, the 95% MDC values for temporal and spatial gait parameters of older community-dwelling adults were more responsive to change than those obtained by the Stopwatch-footfall technique. Clinicians should recognize that self-selected walking speed, cadence, and stride length when obtained by an instrumented walkway must be equal to or exceed 12.6 cm/s, 8.4 steps/min, or 7 cm, respectively, for the change to be considered real change and not from measurement error.
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agreement between the gaitrite walkway system and a Stopwatch footfall count method for measurement of temporal and spatial gait parameters
Archives of Physical Medicine and Rehabilitation, 2006Co-Authors: James W. Youdas, John H. Hollman, Monica J. Aalbers, Holly N. Ahrenholz, Rebecca A. Aten, Joseph J. CremersAbstract:Abstract Youdas JW, Hollman JH, Aalbers MJ, Ahrenholz HN, Aten RA, Cremers JJ. Agreement between the GAITRite walkway system and a Stopwatch–footfall count method for measurement of temporal and spatial gait parameters. Objective To determine the agreement for measurements of stride length, cadence, and walking speed obtained from the GAITRite system and the Stopwatch–footfall count technique. Design Criterion standard. Setting Research laboratory in a physical therapy education program. Participants Forty healthy volunteers (13 men, 27 women) without lower-extremity injury. Interventions Participants walked across a GAITRite mat with embedded pressure sensors at their self-selected walking speed. Simultaneously, an examiner used a Stopwatch to record the elapsed time necessary to cross the mat and counted the number of complete footfalls. Main Outcome Measures Walking speed, cadence, and stride-length measures were compared between the GAITRite system and the Stopwatch–footfall count technique. Results Correlation coefficients comparing both systems were .97 for walking speed, .75 for cadence, and .85 for stride length. Ninety-five percent of the time we would expect the between-methods differences to range between .09 and −.05m/s for walking speed, between −1.5 and −24.3 steps/min for cadence, and between .01 and .37m for stride length. Conclusions This study shows that the GAITRite and Stopwatch–footfall count methods lack clinically acceptable agreement for the measurements of cadence and stride length in a group of healthy volunteers walking at their self-selected speeds. Clinicians who require precise measurement of cadence and stride length should consider using the GAITRite system instead of the Stopwatch–footfall count technique.
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Agreement Between the GAITRite Walkway System and a Stopwatch–Footfall Count Method for Measurement of Temporal and Spatial Gait Parameters
Archives of physical medicine and rehabilitation, 2006Co-Authors: James W. Youdas, John H. Hollman, Monica J. Aalbers, Holly N. Ahrenholz, Rebecca A. Aten, Joseph J. CremersAbstract:Abstract Youdas JW, Hollman JH, Aalbers MJ, Ahrenholz HN, Aten RA, Cremers JJ. Agreement between the GAITRite walkway system and a Stopwatch–footfall count method for measurement of temporal and spatial gait parameters. Objective To determine the agreement for measurements of stride length, cadence, and walking speed obtained from the GAITRite system and the Stopwatch–footfall count technique. Design Criterion standard. Setting Research laboratory in a physical therapy education program. Participants Forty healthy volunteers (13 men, 27 women) without lower-extremity injury. Interventions Participants walked across a GAITRite mat with embedded pressure sensors at their self-selected walking speed. Simultaneously, an examiner used a Stopwatch to record the elapsed time necessary to cross the mat and counted the number of complete footfalls. Main Outcome Measures Walking speed, cadence, and stride-length measures were compared between the GAITRite system and the Stopwatch–footfall count technique. Results Correlation coefficients comparing both systems were .97 for walking speed, .75 for cadence, and .85 for stride length. Ninety-five percent of the time we would expect the between-methods differences to range between .09 and −.05m/s for walking speed, between −1.5 and −24.3 steps/min for cadence, and between .01 and .37m for stride length. Conclusions This study shows that the GAITRite and Stopwatch–footfall count methods lack clinically acceptable agreement for the measurements of cadence and stride length in a group of healthy volunteers walking at their self-selected speeds. Clinicians who require precise measurement of cadence and stride length should consider using the GAITRite system instead of the Stopwatch–footfall count technique.
Didier Lime - One of the best experts on this subject based on the ideXlab platform.
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Symbolic unfolding of parametric Stopwatch Petri nets
Formal Methods in System Design, 2013Co-Authors: Claude Jard, Didier Lime, Olivier H. Roux, Louis-marie TraonouezAbstract:We address the problem of unfolding safe parametric Stopwatch time Petri nets (PSwPNs), i.e., safe time Petri nets (TPNs) possibly extended with time parameters and Stopwatches. We extend the notion of branching process to account for the dates of the occurrences of events and thus define a symbolic unfolding for PSwPNs. In the case of TPNs we also propose a method based on our so-called time branching processes to compute a finite complete prefix of the symbolic unfolding. The originality of our work relies on a precise handling of direct conflicts between events, and the analysis of their effects on the constraints between the firing dates of those events.
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Symbolic Unfolding of Parametric Stopwatch Petri Nets
2010Co-Authors: Louis-marie Traonouez, Didier Lime, Claude Jard, Bartosz Grabiec, Olivier H. RouxAbstract:This paper proposes a new method to compute symbolic unfoldings for safe Stopwatch Petri Nets (SwPNs), extended with time parameters, that symbolically handle both the time and the parameters. We propose a concurrent semantics for (parametric) SwPNs in terms of timed processes à la Aura and Lilius. We then show how to compute a symbolic unfolding for such nets, as well as, for the subclass of safe time Petri nets, how to compute a finite complete prefix of this unfolding. Our contribution is threefold: unfolding in the presence of Stopwatches or parameters has never been addressed before. Also in the case of time Petri nets, the proposed unfolding has no duplication of transitions and does not require read arcs and as such its computation is more local. Finally the unfolding method is implemented (for time Petri nets) in the tool Romeo.
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TACAS - Romeo: A Parametric Model-Checker for Petri Nets with Stopwatches
Tools and Algorithms for the Construction and Analysis of Systems, 2009Co-Authors: Didier Lime, Olivier Roux, Charlotte Seidner, Louis-marie TraonouezAbstract:Last time we reported on Romeo, analyses with this tool were mostly based on translations to other tools. This new version provides an integrated TCTL model-checker and has gained in expressivity with the addition of parameters. Although there exists other tools to compute the state-space of Stopwatch models, Romeo is the first one that performs TCTL model-checking on Stopwatch models. Moreover, it is the first tool that performs TCTL model-checking on timed parametric models. Indeed, Romeo now features an efficient model-checking of time Petri nets using the Uppaal DBM Library, the model-checking of Stopwatch Petri nets and parametric Stopwatch Petri nets using the Parma Polyhedra Library and a graphical editor and simulator of these models. Furthermore, its audience has increased leading to several industrial contracts. This paper reports on these recent developments of Romeo.
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Parametric Model-Checking of Stopwatch Petri Nets
Journal of Universal Computer Science, 2009Co-Authors: Louis-marie Traonouez, Didier Lime, Olivier RouxAbstract:At the border between control and verification, parametric verification can be used to synthesize constraints on the parameters to ensure that a system verifies given specifications. In this paper we propose a new framework for the parametric verification of time Petri nets with Stopwatches. We first introduce a parametric exten- sion of time Petri nets with inhibitor arcs (ITPNs) with temporal parameters and we define a symbolic representation of the parametric state-space based on the classical state-class graph method. Then, we propose semi-algorithms for the parametric model- checking of a subset of parametric TCTL formulae on ITPNs. These results have been implemented in the tool Romeo and we illustrate them in a case-study based on a scheduling problem.
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RTSS - A translation based method for the timed analysis of scheduling extended time Petri nets
25th IEEE International Real-Time Systems Symposium, 1Co-Authors: Didier Lime, Olivier RouxAbstract:In this paper, we present a method for the timed analysis of real-time systems, taking into account the scheduling constraints. The model considered is an extension of time Petri nets, scheduling extended time Petri nets (SETPN) for which the valuations of transitions may be stopped and resumed, thus allowing the modelling of preemption. This model has a great expressivity and allows a very natural modelling. The method we propose consists of precomputing, with a fast algorithm, the state space of the SETPN as a Stopwatch automaton (SWA). This Stopwatch automaton is proven timed bisimilar to the SETPN, so we can perform the timed analysis of the SETPN through it with the tool on linear hybrid automata, HYTECH. The main interests of this precomputation are that it is fast because it is difference bounds matrix (DBM)-based, and that it has online Stopwatch reduction mechanisms. Consequently, the resulting Stopwatch automaton has, in the general case, a fairly lower number of Stopwatches than what could be obtained by a direct modelling of the system as SWA. Since the number of Stopwatches is critical for the complexity of the verification, the method increases the efficiency of the timed analysis of the system, and in some cases may just make it possible at all.
