Annalisa Bossi - Academia.edu (original) (raw)

Papers by Annalisa Bossi

International Logic Programming Symposium/International Symposium on Logic Programming/North American Conference on Logic Programming/Symposium on Logic Programming, 1997

International Journal of Radiation Oncology*Biology*Physics, 2009

kinetics after radiation treatment was an exponential decay or not. The PSA data were fitted to e... more kinetics after radiation treatment was an exponential decay or not. The PSA data were fitted to exponential decay curves and exponential decay behavior was assigned if the mathematical fits were close enough to the data. This proximity criteria was based on residual differences and coefficients of correlation. Chi Square tests (two sided) were used to compare patients with an exponential decay vs. a non-exponential decay. A general linear modelling for repeated measures was used to analyze the influence of various factors on 7 PSA measurements: pre-EBRT PSA and the following 6 post-EBRT measurements. Spearman rank correlation was used to identify an association between different pre-EBRT factors and the PSA nadir. Results: Median follow-up after for all patients was 163.14 weeks (range 92-265). Patients with an exponential decay (n = 56) were significantly older (median 72y) vs. patients with a non-exponential decay (n = 11, median 65y, p = 0.025). Patients exhibiting a mathematically sound exponential decay also had a significantly higher number of positive biopsies (3 vs. 2, p = 0.013). PSA nadir (0.42 vs. 0.39, p = 0.324) and time to nadir (122.1 vs. 124.1, p = 0.428) did not differ between both groups. Linear modeling showed that prostate volume and PSA density (both p\0.001) as well as BMI (p = 0.026) and age (p = 0.019) all had a significant influence on all 7 PSA measurements. The PSA nadir was positively correlated with PSA density (r=0.315, p = 0.009) but not with PSA half-life, EBRT dose, pre EBRT PSA, Gleason or BMI (p = 0.109-0.988). We also found that the longer the time to nadir, the smaller the value of the PSA nadir (r=-0.421, p\0.001). Conclusions: These observations suggest that an exponential decay behavior does not have an influence on the PSA nadir, a surrogate marker for disease free survival. Our data suggest that the PSA post-EBRT is influenced by factors linked to the tumor-load but also patient-specific factors. These findings could help in understanding PSA bounce and eventually in models for cellular death.

International Journal of Radiation Oncology*Biology*Physics, 2009

centimeters. The volume of the prostate gland receiving 100% of prescription dose (V100) and the ... more centimeters. The volume of the prostate gland receiving 100% of prescription dose (V100) and the dose delivered to 90% of the gland (D90) were also calculated. Results: The mean prostate volume was 34.5 cm 3 with a mean time to post-implant CT of 29.5 days. For I-125, the V100 increased from 90.2 to 94.9% from the lowest to the highest activity seeds (p = \0.001) and D90 increased from 102.4% to 108.5% (p = 0.005). For Pd-103, the V100 and D90 increased from 87.2% and 97.6% to 89.0% and 101.4%, respectively (p = 0.006 and p = 0.010). In contrast, there was no clear correlation between seed activity and R100. For I-125, the mean R100 was 0.75, 1.07 and 0.72 cm 3 for the low, intermediate and high activity seeds (p = 0.008). For Pd-103, the mean R100 was 0.47, 0.85 and 0.80 cm 3 for the low, intermediate and high activity seeds (p = 0.186). Conclusions: On average, the V100 and D90 statistically increased with higher activity seeds while there was no statistical trend for increased rectal doses based on either Pd-103 or I-125 seed activity. Within the confines of the seed activities used in this study, these results indicate that higher activity seeds may result in better post-implant prostate dosimetry without a deleterious effect on rectal dose.

In this chapter we show a semantics for pure logic programs which correctly models computed answe... more In this chapter we show a semantics for pure logic programs which correctly models computed answer substitutions and which is compositional wrt union of programs (i.e. OR-compositional). According to the general approach described in 15], the semantics is based on a domain which consists of sets of (equivalence classes of) clauses. We rst de ne an operational version O (P) of the semantics and we prove its compositionality. Then we show a xpoint semantics F (P), originally introduced in 5], and we prove its equivalence to the operational semantics. From the model-theoretic viewpoint, the compositional semantics is mapped onto a set of Herbrand interpretations, thus leading to a de nition of -model and to a model-theoretic semantics which are still based on the classical notion of truth and which are compositional wrt program union. Finally some applications of our semantics are discussed. This chapter is a restricted version of 3].

Acm Sigsam Bulletin, Nov 1, 1980

The problem considered in the present paper concerns a structural identifiability test for an app... more The problem considered in the present paper concerns a structural identifiability test for an appealing class of mathematical models, the so called compartmental models, which are widely employed in several fields of biology, medicine, ecology, etc.

Proceedings. 17th IEEE Computer Security Foundations Workshop, 2004., 2000

Information flow security properties such as noninterference ensure the protection of confidentia... more Information flow security properties such as noninterference ensure the protection of confidential data by strongly limiting the flow of sensitive information. However, to deal with real applications, it is often necessary to admit mechanisms for downgrading or declassifying information.

Proceedings of the 20th Acm Sigplan Sigact Symposium on Principles of Programming Languages, 1993

In this paper we de ne a compositional semantics for a generalized composition operator on logic ... more In this paper we de ne a compositional semantics for a generalized composition operator on logic programs. Static and dynamic inheritance as well as composition by union of clauses can all be obtained by specializing the general operator. The semantics is based on the notion of di erential programs, logic programs annotated with declarations that establish the programs' external interfaces.

Flow Turbul Combust, Jun 22, 2000

Proceedings of the 7th International Workshop on Logic Programming Synthesis and Transformation, Jul 10, 1997

We try to formalize the intuitive reasoning which we normally use to get convinced that a query h... more We try to formalize the intuitive reasoning which we normally use to get convinced that a query has successful LD-derivations in a program. To this purpose we de ne the class of programs and queries without failures which have the property of not having nitely failing derivations. Such property is simple to verify, it is preserved through leftmost unfolding and it can be useful both in verifying properties of logic programs and in program transformation. The class of programs without failures is very restricted but in program transformations it is su cient that only some predicates in the program are in the class.

Lopstr, 2004

Most logic programming languages actually provide some kind of dynamic scheduling to increase the... more Most logic programming languages actually provide some kind of dynamic scheduling to increase the expressive power and to control execution. Input consuming derivations have been introduced to describe dynamic scheduling while abstracting from the technical details. In this paper we review and compare the different proposals given in [9], [10] and [12] for denotational semantics of programs with input consuming derivations. We also show how they can be applied to termination analysis.

Theory and Practice of Logic Programming, May 1, 2002

We propose a modular method for proving termination of general logic programs (i.e., logic progra... more We propose a modular method for proving termination of general logic programs (i.e., logic programs with negation). It is based on the notion of acceptable programs, but it allows us to prove termination in a truly modular way. We consider programs consisting of a hierarchy of modules and supply a general result for proving termination by dealing with each module separately. For programs which are in a certain sense well-behaved, namely well-moded or well-typed programs, we derive both a simple verification technique and an iterative proof method. Some examples show how our system allows for greatly simplified proofs.

International Journal of Intelligent Systems, 1993

ABSTRACT The purpose of this paper is to make a contribution towards the integration of Object-Or... more ABSTRACT The purpose of this paper is to make a contribution towards the integration of Object-Orientation and logic programming. We introduce the notion of differential programs, logic programs annotated to make their external interfaces explicit. Similarly to classes in the O-O paradigm, differential programs can be organized in isa hierarchies. The isa-composition of differential programs captures the semantics of several mechanisms such as static and dynamic overriding inheritance as well as a form of extension inheritance defined in term of composition by union of clauses. The application of the programming discipline we propose is illustrated on a concrete programming example. We give a proof-theoretic semantics for isa-hierarchies: we define an inference system which extends SLD resolution to take into account the inheritance mechanisms encompassed by the isa operator. Then we introduce a corresponding operator which provides a syntactic counterpart of the isa-composition. The new operator, denoted by ! , transforms any isa hierarchy HP into an equivalent "flat" program HP / whose proof theoretic semantics is defined in terms of the standard notion of SLD derivation. Finally we define a fixed point semantics which is ! - compositional and which models correctly the answer substitutions of programs. By virtue of the aforesaid correspondence between isa-hierarchies and !-composite programs, we obtain a compositional semantics for isa hierarchies. The semantics of differential programs generalizes previous work on OR-compositional semantics for logic programs. It is obtained by resorting to the notion of context-sensitive interpretations, an extension of the\Omega\Gamma/38783/-132 of [3] defined as sets of non-ground clauses. 1991 Mathematics Subject Classification: 68N1...

Information flow security in a multilevel system aims at guaranteeing that no high level informat... more Information flow security in a multilevel system aims at guaranteeing that no high level information is revealed to low levels. A usual requirement to ensure information flow security for a process is that no generic attacker can induce a high-to-low information flow. This requirement is too demanding when we have some knowledge about the contexts where the process is going

In logic programming, dynamic scheduling refers to a situation where the selection of the atom in... more In logic programming, dynamic scheduling refers to a situation where the selection of the atom in each resolution (computation) step is determined at runtime, as opposed to a fixed selection rule such as the left-to-right one of Prolog. This has applications e.g. in parallel programming. A mechanism to control dynamic scheduling is provided in existing languages in the form of delay declarations.

In logic programming, dynamic scheduling indicates the feature by means of which the choice of th... more In logic programming, dynamic scheduling indicates the feature by means of which the choice of the atom to be selected at each resolution step is done at runtime and does not follow a fixed selection rule such as the leftto-right one of Prolog. Input consuming derivations were introduced to model dynamic scheduling while abstracting from the technical details. In this article, we provide a sufficient and necessary criterion for termination of input consuming derivations of simply moded logic programs. The termination criterion we propose is based on a denotational semantics for partial derivations which is defined in the spirit of model-theoretic semantics previously proposed for left-to-right derivations.

Abstract: Information ow security in a multilevel system aims at guaranteeingthat no high level i... more Abstract: Information ow security in a multilevel system aims at guaranteeingthat no high level information is revealed to low level users,even in the presence of any possible malicious process. Persistent BNDC(P BNDC, for short) is an information-ow security property which issuitable to deal with processes in dynamic contexts. In this work weshow that P BNDC is compositional with respect to

International Logic Programming Symposium/International Symposium on Logic Programming/North American Conference on Logic Programming/Symposium on Logic Programming, 1997

International Journal of Radiation Oncology*Biology*Physics, 2009

kinetics after radiation treatment was an exponential decay or not. The PSA data were fitted to e... more kinetics after radiation treatment was an exponential decay or not. The PSA data were fitted to exponential decay curves and exponential decay behavior was assigned if the mathematical fits were close enough to the data. This proximity criteria was based on residual differences and coefficients of correlation. Chi Square tests (two sided) were used to compare patients with an exponential decay vs. a non-exponential decay. A general linear modelling for repeated measures was used to analyze the influence of various factors on 7 PSA measurements: pre-EBRT PSA and the following 6 post-EBRT measurements. Spearman rank correlation was used to identify an association between different pre-EBRT factors and the PSA nadir. Results: Median follow-up after for all patients was 163.14 weeks (range 92-265). Patients with an exponential decay (n = 56) were significantly older (median 72y) vs. patients with a non-exponential decay (n = 11, median 65y, p = 0.025). Patients exhibiting a mathematically sound exponential decay also had a significantly higher number of positive biopsies (3 vs. 2, p = 0.013). PSA nadir (0.42 vs. 0.39, p = 0.324) and time to nadir (122.1 vs. 124.1, p = 0.428) did not differ between both groups. Linear modeling showed that prostate volume and PSA density (both p\0.001) as well as BMI (p = 0.026) and age (p = 0.019) all had a significant influence on all 7 PSA measurements. The PSA nadir was positively correlated with PSA density (r=0.315, p = 0.009) but not with PSA half-life, EBRT dose, pre EBRT PSA, Gleason or BMI (p = 0.109-0.988). We also found that the longer the time to nadir, the smaller the value of the PSA nadir (r=-0.421, p\0.001). Conclusions: These observations suggest that an exponential decay behavior does not have an influence on the PSA nadir, a surrogate marker for disease free survival. Our data suggest that the PSA post-EBRT is influenced by factors linked to the tumor-load but also patient-specific factors. These findings could help in understanding PSA bounce and eventually in models for cellular death.

International Journal of Radiation Oncology*Biology*Physics, 2009

centimeters. The volume of the prostate gland receiving 100% of prescription dose (V100) and the ... more centimeters. The volume of the prostate gland receiving 100% of prescription dose (V100) and the dose delivered to 90% of the gland (D90) were also calculated. Results: The mean prostate volume was 34.5 cm 3 with a mean time to post-implant CT of 29.5 days. For I-125, the V100 increased from 90.2 to 94.9% from the lowest to the highest activity seeds (p = \0.001) and D90 increased from 102.4% to 108.5% (p = 0.005). For Pd-103, the V100 and D90 increased from 87.2% and 97.6% to 89.0% and 101.4%, respectively (p = 0.006 and p = 0.010). In contrast, there was no clear correlation between seed activity and R100. For I-125, the mean R100 was 0.75, 1.07 and 0.72 cm 3 for the low, intermediate and high activity seeds (p = 0.008). For Pd-103, the mean R100 was 0.47, 0.85 and 0.80 cm 3 for the low, intermediate and high activity seeds (p = 0.186). Conclusions: On average, the V100 and D90 statistically increased with higher activity seeds while there was no statistical trend for increased rectal doses based on either Pd-103 or I-125 seed activity. Within the confines of the seed activities used in this study, these results indicate that higher activity seeds may result in better post-implant prostate dosimetry without a deleterious effect on rectal dose.

In this chapter we show a semantics for pure logic programs which correctly models computed answe... more In this chapter we show a semantics for pure logic programs which correctly models computed answer substitutions and which is compositional wrt union of programs (i.e. OR-compositional). According to the general approach described in 15], the semantics is based on a domain which consists of sets of (equivalence classes of) clauses. We rst de ne an operational version O (P) of the semantics and we prove its compositionality. Then we show a xpoint semantics F (P), originally introduced in 5], and we prove its equivalence to the operational semantics. From the model-theoretic viewpoint, the compositional semantics is mapped onto a set of Herbrand interpretations, thus leading to a de nition of -model and to a model-theoretic semantics which are still based on the classical notion of truth and which are compositional wrt program union. Finally some applications of our semantics are discussed. This chapter is a restricted version of 3].

Acm Sigsam Bulletin, Nov 1, 1980

The problem considered in the present paper concerns a structural identifiability test for an app... more The problem considered in the present paper concerns a structural identifiability test for an appealing class of mathematical models, the so called compartmental models, which are widely employed in several fields of biology, medicine, ecology, etc.

Proceedings. 17th IEEE Computer Security Foundations Workshop, 2004., 2000

Information flow security properties such as noninterference ensure the protection of confidentia... more Information flow security properties such as noninterference ensure the protection of confidential data by strongly limiting the flow of sensitive information. However, to deal with real applications, it is often necessary to admit mechanisms for downgrading or declassifying information.

Proceedings of the 20th Acm Sigplan Sigact Symposium on Principles of Programming Languages, 1993

In this paper we de ne a compositional semantics for a generalized composition operator on logic ... more In this paper we de ne a compositional semantics for a generalized composition operator on logic programs. Static and dynamic inheritance as well as composition by union of clauses can all be obtained by specializing the general operator. The semantics is based on the notion of di erential programs, logic programs annotated with declarations that establish the programs' external interfaces.

Flow Turbul Combust, Jun 22, 2000

Proceedings of the 7th International Workshop on Logic Programming Synthesis and Transformation, Jul 10, 1997

We try to formalize the intuitive reasoning which we normally use to get convinced that a query h... more We try to formalize the intuitive reasoning which we normally use to get convinced that a query has successful LD-derivations in a program. To this purpose we de ne the class of programs and queries without failures which have the property of not having nitely failing derivations. Such property is simple to verify, it is preserved through leftmost unfolding and it can be useful both in verifying properties of logic programs and in program transformation. The class of programs without failures is very restricted but in program transformations it is su cient that only some predicates in the program are in the class.

Lopstr, 2004

Most logic programming languages actually provide some kind of dynamic scheduling to increase the... more Most logic programming languages actually provide some kind of dynamic scheduling to increase the expressive power and to control execution. Input consuming derivations have been introduced to describe dynamic scheduling while abstracting from the technical details. In this paper we review and compare the different proposals given in [9], [10] and [12] for denotational semantics of programs with input consuming derivations. We also show how they can be applied to termination analysis.

Theory and Practice of Logic Programming, May 1, 2002

We propose a modular method for proving termination of general logic programs (i.e., logic progra... more We propose a modular method for proving termination of general logic programs (i.e., logic programs with negation). It is based on the notion of acceptable programs, but it allows us to prove termination in a truly modular way. We consider programs consisting of a hierarchy of modules and supply a general result for proving termination by dealing with each module separately. For programs which are in a certain sense well-behaved, namely well-moded or well-typed programs, we derive both a simple verification technique and an iterative proof method. Some examples show how our system allows for greatly simplified proofs.

International Journal of Intelligent Systems, 1993

ABSTRACT The purpose of this paper is to make a contribution towards the integration of Object-Or... more ABSTRACT The purpose of this paper is to make a contribution towards the integration of Object-Orientation and logic programming. We introduce the notion of differential programs, logic programs annotated to make their external interfaces explicit. Similarly to classes in the O-O paradigm, differential programs can be organized in isa hierarchies. The isa-composition of differential programs captures the semantics of several mechanisms such as static and dynamic overriding inheritance as well as a form of extension inheritance defined in term of composition by union of clauses. The application of the programming discipline we propose is illustrated on a concrete programming example. We give a proof-theoretic semantics for isa-hierarchies: we define an inference system which extends SLD resolution to take into account the inheritance mechanisms encompassed by the isa operator. Then we introduce a corresponding operator which provides a syntactic counterpart of the isa-composition. The new operator, denoted by ! , transforms any isa hierarchy HP into an equivalent "flat" program HP / whose proof theoretic semantics is defined in terms of the standard notion of SLD derivation. Finally we define a fixed point semantics which is ! - compositional and which models correctly the answer substitutions of programs. By virtue of the aforesaid correspondence between isa-hierarchies and !-composite programs, we obtain a compositional semantics for isa hierarchies. The semantics of differential programs generalizes previous work on OR-compositional semantics for logic programs. It is obtained by resorting to the notion of context-sensitive interpretations, an extension of the\Omega\Gamma/38783/-132 of [3] defined as sets of non-ground clauses. 1991 Mathematics Subject Classification: 68N1...

Information flow security in a multilevel system aims at guaranteeing that no high level informat... more Information flow security in a multilevel system aims at guaranteeing that no high level information is revealed to low levels. A usual requirement to ensure information flow security for a process is that no generic attacker can induce a high-to-low information flow. This requirement is too demanding when we have some knowledge about the contexts where the process is going

In logic programming, dynamic scheduling refers to a situation where the selection of the atom in... more In logic programming, dynamic scheduling refers to a situation where the selection of the atom in each resolution (computation) step is determined at runtime, as opposed to a fixed selection rule such as the left-to-right one of Prolog. This has applications e.g. in parallel programming. A mechanism to control dynamic scheduling is provided in existing languages in the form of delay declarations.

In logic programming, dynamic scheduling indicates the feature by means of which the choice of th... more In logic programming, dynamic scheduling indicates the feature by means of which the choice of the atom to be selected at each resolution step is done at runtime and does not follow a fixed selection rule such as the leftto-right one of Prolog. Input consuming derivations were introduced to model dynamic scheduling while abstracting from the technical details. In this article, we provide a sufficient and necessary criterion for termination of input consuming derivations of simply moded logic programs. The termination criterion we propose is based on a denotational semantics for partial derivations which is defined in the spirit of model-theoretic semantics previously proposed for left-to-right derivations.

Abstract: Information ow security in a multilevel system aims at guaranteeingthat no high level i... more Abstract: Information ow security in a multilevel system aims at guaranteeingthat no high level information is revealed to low level users,even in the presence of any possible malicious process. Persistent BNDC(P BNDC, for short) is an information-ow security property which issuitable to deal with processes in dynamic contexts. In this work weshow that P BNDC is compositional with respect to