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Up: Temporal Reasoning for Diagnosis
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The first step in the diagnostic process is to draw any definite
conclusions from the input. In the example, these are:
- chest pain
MI
- PCWP = 12
(high LAP)=false 
- rales PC
- nitroglycerin
Since the chest pain is a symptom with immediate effect and no
persistence, the time of the chest pain determines the time of the MI.
Not all MI's have chest pain, so this is only true when the MI causes
chest pain. The rales are an observation on physical exam, so it does
not determine the time extent of the PC. All we know from the rales is
that the PC started before now and will end after now. The
PCWP is a test which happened now, and thus is just like an
observation.