# History Taking: Tensors
## The important layers of communication

The first step in any patient-interaction is to understand the patient's situation.
The process of understanding this situation is typically called the *history of present illness*, or HPI.
This HPI is the seed for further focused effort in treating the patient.

The process of taking an HPI is historically framed in steps.

## Model
We take a tensor model to highlight the important structures of the HPI.
A tensor is, in general, a pattern with many interacting parts.
Unlike a vector, a tensor does not necessarily have numbers intrinsically associated with it.
It only has numbers once you've chosen to view it from a specific perspective.

While the tensor itself assumes a specific structure, this specific structure does not hinder the generalizability of the core objects of interest: the encoding, communication, and decoding of the patient's situation.

## Intention Tensor
We start with the patient's intrinsic *intention tensor*.
The goal of the HPI is to infer this intention tensor for further downstream diagnosis and management.

##