S3-07 · 进阶 S3-07 · Advanced

注意力分数 · 一条粗线是怎样算出来的 Attention Score · How a Thick Line Gets Its Number

Q · K → scale by √dk → softmax → attention weight → line width

注意力分数是查询与键的匹配值经缩放和归一化后形成的权重。它把点积、softmax 与可见线宽接成一条可核对的因果链。 An attention score becomes a weight after the Query–Key match is scaled and normalized. It connects dot product, softmax, and visible line width into one checkable causal chain.

01 · 粗线背后有账本 01 · Every thick line has a ledger

为什么某条注意力线是 8.1 px,而不是凭感觉画粗一点? Why is one attention line 8.1 px wide instead of simply “drawn a bit thicker”?

02 点击一条线,展开四格账本 Select a Line and Unfold Its Four-Cell Ledger

点积 → 线宽 Dot product → width
① 点积 ① Dot product
Q · K
② 缩放 ② Scaled
÷ √2
③ 权重 → ④ 线宽 ③ Weight → ④ Width

复用 S3 线宽语法:lineWidth = 1.5 + weight × 10。只有 softmax 后的非负权重进入线宽。 S3 line grammar reused: lineWidth = 1.5 + weight × 10. Only nonnegative post-softmax weights enter line width.

03 从匹配值到可见线宽的 4 格 Four Cells from Match Value to Visible Width

逐格可审计 Auditable cell by cell
CELL 01

点积 Dot product

Q 的两个分量与 K 的两个分量分别相乘再相加。 Multiply the two Q and K component pairs, then add them.

CELL 02

缩放 Scale

除以 √dk,避免维度大时点积过尖。 Divide by √dk so large dimensions do not make scores too sharp.

CELL 03

Softmax

所有候选一起归一化为总和 1 的非负权重。 Normalize all candidates together into nonnegative weights summing to one.

CELL 04

线宽 Line width

统一映射把同一个权重变成可比较的粗细。 One shared mapping turns that weight into comparable thickness.

04 最小机制:三步计算,一步显示 Minimal Mechanism: Three Calculations, One Display

α = softmax(QKT / √dk)
Q · Ki → si/√2 → αi → 1.5 + 10αi
点击不同线,前三格来自计算,最后一格只负责把 α 变成画面语言。 Select different lines. The first three cells are computation; the last only translates α into visual language.
Q · K 得到可正可负的匹配值 A signed match value
÷ √dk 控制分数尺度 Control score scale
softmax → px 权重竞争后再画线 Compete, normalize, then draw

05 边界实验:跳过缩放与 softmax 直接画线 Boundary Test: Draw Raw Scores Without Scaling or Softmax

主动制造失败 Create a failure

原始点积可能为负,也不保证总和为 1 Raw dot products may be negative and do not sum to one

把三个点积直接当权重。负分无法成为负线宽,正分总和也不等于 100%,可视语法失去统一意义。 Treat the three dot products as weights. A negative score cannot become negative width, and positive scores do not sum to 100%, so the visual grammar loses meaning.

尚未执行。正常线宽只接受 softmax 后权重。 Not run yet. Normal line width uses post-softmax weights only.
点积就是最终注意力权重。 The dot product is the final attention weight. → ✓ 它还要经过缩放与候选间归一化。 It still needs scaling and cross-candidate normalization.
每条线可以独立做 softmax。 Each line can run softmax alone. → ✓ 候选必须一起竞争,总和才为 1。 Candidates compete together so weights sum to one.
粗细只是装饰。 Thickness is decorative. → ✓ 同一公式把权重机械映射成线宽。 One formula mechanically maps weight to width.
06 · 一句话带走 06 · One line to keep

注意力权重来自 Q-K 点积、缩放与 softmax;点击任一连线,就能把数值一路核对到最终线宽。 Attention weight comes from Q–K dot product, scaling, and softmax. Select any line to audit its numbers all the way to final width.