Negation Null Values Rough chalk talk notes Alan
- Slides: 21
Negation & Null Values Rough “chalk talk” notes Alan Rector 2005 -05 -28 (revised 2005 -06 -12) 1
Simple Version • Case 1: Diabetes – “Some people have diabetes & some people don’t” • xy. [Person(x) & Diabetes(y) & has(x, y)] x. [Person(x) & NOT y. [ Diabetes(y) & has(x, y)]] – “john has diabetes” • Person(john) & y[Diabetes(y) & has(john, y)] – “john does not have diabetes” • Person(john) & NOT y[Diabetes(y) & has(john, y)] 2
Simple Version 2: • Temperature – “All people have a temperature that has a temperature value” • x. Person(x) yz. Temperature(y) & Temperature_value(z) & has_observable(x, y) & has_value(y, z) – John has a temperature of 37 • Person(john) & y. Temperature(y) & Temperature_value(37_degrees) & has_observable(john, y) & has_value(y, 37_degrees). 3
Simple Negation NOT Informative Negates too much • Temperature – John has a temperature that is an elevated temperature • Person(john) & yz. Temperature(y) & Temperature_value(z) & has_observable(john, y) & has_value(y, z) & elevated_for(y, z). – John does not have a temperature that is an elevated temperature • Person(john) & NOT yz. Temperature(y) & Temperature_value(z) & has_observable(john, y) & has_value(y, z) & elevated_for(y, z). 4
Alternative value rather than negation • “John has a Temperature that is not elevated”: • Person(john) & yz. Temperature(y) & Temperature_value(z) & has_observable(john, y) & has_value(y, z) & NOT elevated_for(y, z). 5
Information loss with negation – y. Termperature(y) & Temperature_value(z) elevated_for(y, z) OR normal_for(y, z) OR depressed_for(y, z) – Therefore, NOT elevated does not convey (usually) all the information available • To specify all specify the information available, give the most specific value available: “John has a temperature that is depressed” – Person(john) & NOT yz. Temperature(y) & Temperature_value(z) & has_observable(john, y) & has_value(y, z) & depressed_for(y, z). 6
Pedal Pulses Just a special case with two values: present/absent • “All people can have observations of pedal pulses that can be present or absent” • x. Person(x) yz. Pedal_pulse(y) & Present_absent(z) & has_observable(x, y) & has_value(y, z) – “John’s pedal pulse is present” • Person(john) & y. Pedal_pulse(y) & Present_absent(present) & has_observable(john, y) & has_value(y, present). – “John’s pedal pulse is absent” • Person(john) & y. Pedal_pulse(y) & Present_absent(absent) & has_observable(john, y) & has_value(y, absent). 7
Flavours of Null – “Some people with non-null observational status have diabetes) • xy. Person(x) & Diabetes(y) & non_null(x, Diabetes) & has(x, y) – “john can be determined to have and has diabetes” • Person(john) & non_null(john, Diabetes) & y. Diabetes(y)& has(john, y) – “john does not have diabetes” • Person(john) & non_null(john, Diabetes) & NOT y. Diabetes(y) & has(john, y) – “Whether or not john has diabetes cannot be determined” • Person john & NOT non_null(john, Diabetes) 8
Flavours of Null • Temperature – “All people that have non-null temperature measurement have a temperature that has a temperature value” • x. Person(x) & non. Null(x, Temperature) yz. Temperature(y) & Temperature_value(z) & has_observable(x, y) & has_value(y, z) – John has a temperature of 37 • Person(john) & non. Null(x, Temperature) y. Temperature(y) & Temperature_value(37_degrees) & has_observable(john, y) & has_value(y, 37_degrees). 9
Flavours of Null: Pedal Pulses • “All people who’s pedal pulses might be reasonably measure can have observations of pedal pulses that can be present or absent” • x. Person(x) & non. Null(x, Pedal_pulse) yz. Pedal_pulse(y) & Present_absent(z) & has_observable(x, y) & has_value(y, z) 10
Non-null – what does it really mean? • Physical_possibility_status(Person, Entity) “applicability” – Refers to the patient • E. g. Pedal pulses in a bilateral amputee • Epistemic_status(Observer, <Person, Entity>) “validity” – Refers to the observation, method, and sample • E. g. Could not get a clear answer; dropped specimen; haemolised; etc • null. Status = applicability x validity 11
Hypothesis • “Applicability” belongs to the clinical realm and hence to S-CT – A statement about the patient that they atypically do not have this observable� • They are an atypical patient with respect to this observable • “Validity” belongs to the knowing realm & hence to HL 7 (or other info model) – About the observation or procedure rather than the patient • The patient may or may not be typical (we don’t know, although they probably are) but our method of knowing went wrong. 12
Including. Validity & applicability • Add the notion that a statement “concerns” a finding / observable • Add a wrapper here called “Clinical_situation” which ‘concerns’ findings/observations. • Some basic rules – If a finding is present then the finding must be applicable to the patient and the situation concerns the finding – A situation may concern a finding that is applicable to a patient but absent – A finding may concern a patient but not be applicable 13
So what is our basic form in a message or EHR • “There is a valid observation by an observer at a time & place with respect to someone/thing of…” – “A clinical situation that • Includes this clinical finding ( is applicable to this patient concerns this finding ) • Does not include this clinical finding but this finding is applicable to this patient ( concerns this finding) • Concerns this clinical finding and that this finding is inapplicable to this patient – “There is a clinical situation that • Includes a observable that is applicable to this patient & has value V ( concerns this observable) • Concerns this observable and that this observable is not applicable to this patient • “There is an invalid observation by an observer at a time & place with respect to someone/thing of – � “A clinical situation that concerns this Observable/Clinical Finding” • The contents are not relevant since the observation is invalid 14
More on negation What are we negating? What does a code represent? • From here on logic notation gets very unreadable – Switch to compact OWL syntax • Roughly outline form with a few extra words – & “and” or “that” – SOME existential (the usual default link in S-CT) • And with apologies for ignorance of some S-CT vocabulary 15
A Rigorous formal Approach to Negation in S-CT using OWL • Hypothesis - a code represents a “Clinical situation” (or “syndrome”) – Already present in the way S-CT is structured • S_CT_Thing & has_morphology SOME Morphology. Class & has_site SOME Anatomical. Structure … – Where role groups are already added • S_CT_Thing & has_rg SOME (Role. Group & has_morphology SOME Morphology. Class & has_site SOME Anatomical. Structure) … 16
So if we identify tentatively for readability and intuitions • Identify – S_CT_Thing Clinical_situation – has_rg includes – Role. Group (in this context) Finding or Observable • Then we have something like – Clinical_situation & includes SOME (Finding has_morphology SOME Morphology. Class & has_site SOME Anatomical. Structure) 17
So “Skull Fracture without Haemorrage” becomes when fully expanded… � – Clinical_situatsion & includes SOME (Finding & has_morphology SOME Fracture & has_site SOME Skull) & NOT includes SOME (Finding & has_morphology SOME Haemorrhage & has_site SOME Skull) • And the rest comes for free – At least as a reference formalism • And for local classification – Well within the capacity of today’s classifiers locally which is all SNOMED needs 18
Demo From Protege-OWl Given a series of definitions of the form: Skull_fracture_without_intracranial_haemorrhage_situation = And underlying definitions such as Intracranial_haemorrhage_finding = 19
Then a flat list of such stated definitions for: 20
Will be rearranged by the OWL classifier to give the correct classification as described in handout automatically 21
- Talk, read talk write template
- Amateurs talk tactics professionals talk logistics
- The words use are not
- Approach chemistry chalk chapter
- Waxy coated paper which transfers pattern markings
- Chalk dust diva
- Paediatric chalk mixture bp
- Diffusible and indiffusible suspension
- Properties of metals nonmetals and semimetals
- Whitaker chalk swindle & schwartz pllc
- Cleavage of chalk
- The chalk machine
- Chalk in vinegar
- Golden door ellis island
- Chalk and board cfa
- Chalk test in ndt
- Tensilon test
- Aulteration
- Western vs eastern values
- Machiavellian personality
- An individual's enduring tendency to feel
- ______ have only two possible values 0 and 1.