# Answer from ChatGPT: Similarity

4 min readMay 27, 2023

….. I am confused: A and B is same victor, but ChatGPT said it is not similar…

how does the dot product represent the similarity?

`The dot product is a mathematical operation that can be used to measure the similarity between two vectors. In the context of attention mechanisms, the dot product is commonly used as a similarity measure between the query vector (Q) and the key vectors (K) to determine the relevance or similarity between them.`

To understand how the dot product represents similarity, let's consider two vectors, A and B, with dimensions n. The dot product between these vectors, denoted as A ⋅ B, is computed as the sum of the element-wise multiplication of the corresponding elements:

A ⋅ B = A[1] * B[1] + A[2] * B[2] + ... + A[n] * B[n]

The dot product can be interpreted as a measure of how much the two vectors align or point in the same direction. If the vectors have similar directions, the dot product will be larger, indicating a higher similarity. Conversely, if the vectors are dissimilar or orthogonal, the dot product will be smaller or close to zero, indicating a lower similarity.

In the context of attention mechanisms, the dot product between the query vector (Q) and each key vector (K) is computed to measure their similarity. By calculating the dot product, we are effectively capturing the alignment or correlation between the query and each key vector, indicating their relevance or similarity in the context of the attention mechanism.

It's important to note that the dot product is just one way to compute similarity, and there are other similarity measures that can be used in different contexts or depending on the requirements of the attention mechanism.

let’s say A=[1,1], B=[1,1], C=[2,2], what is A*B, and A*C?

`To calculate the dot product between two vectors A and B, the dot product is computed as the sum of the element-wise multiplication of the corresponding elements.`

Given A = [1, 1] and B = [1, 1], the dot product A ⋅ B is calculated as follows:

A ⋅ B = A[1] * B[1] + A[2] * B[2]

= 1 * 1 + 1 * 1

= 1 + 1

= 2

So, A ⋅ B = 2.

Similarly, given A = [1, 1] and C = [2, 2], the dot product A ⋅ C is calculated as:

A ⋅ C = A[1] * C[1] + A[2] * C[2]

= 1 * 2 + 1 * 2

= 2 + 2

= 4

So, A ⋅ C = 4.

Therefore, the dot product of A and B is 2, and the dot product of A and C is 4.To calculate the dot product between two vectors A and B, the dot product is computed as the sum of the element-wise multiplication of the corresponding elements.

Given A = [1, 1] and B = [1, 1], the dot product A ⋅ B is calculated as follows:

A ⋅ B = A[1] * B[1] + A[2] * B[2]

= 1 * 1 + 1 * 1

= 1 + 1

= 2

So, A ⋅ B = 2.

Similarly, given A = [1, 1] and C = [2, 2], the dot product A ⋅ C is calculated as:

A ⋅ C = A[1] * C[1] + A[2] * C[2]

= 1 * 2 + 1 * 2

= 2 + 2

= 4

So, A ⋅ C = 4.

Therefore, the dot product of A and B is 2, and the dot product of A and C is 4.

So is A similar to B, or similar to C?

`In terms of the dot product similarity measure, the dot product alone does not provide a direct indication of whether vectors are similar or not. It quantifies the alignment or correlation between vectors but does not provide a direct measure of similarity.`

In the given example, the dot product between A and B is 2, and the dot product between A and C is 4. Since the dot product between A and C is larger than the dot product between A and B, we can say that A is more aligned or correlated with C than with B according to the dot product measure.

However, it is important to note that the dot product is just one way to compute similarity, and its interpretation depends on the specific context and requirements of the application. Other similarity measures, such as cosine similarity or Euclidean distance, might provide different perspectives on the similarity between vectors A, B, and C.

Therefore, based on the dot product similarity measure alone, we can say that A is relatively more similar to C than to B. But to make more definitive conclusions about the overall similarity or dissimilarity between vectors, it's important to consider other similarity measures and additional factors based on the specific application or context.