Value · The Content Retrieved After Matching

01 · 钥匙选中柜门之后 01 · After the key selects a locker

同一把钥匙打开同一扇门，若柜子里的内容换了，为什么取回结果会变，而开门路线不该变？ If the same key opens the same locker but its contents change, why should the retrieved result change while the route stays fixed?

02 只改 Value，盯住不动的连线 Change Value and Watch the Lines Stay Put

QKV 视觉三连 QKV visual trilogy

状态 A Metric A

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状态 B Metric B

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状态 C Metric C

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直接操作主变量，再拖回去验证一句话结论。所有数值均为固定种子的教学模拟。 Operate the main variable, then move it back to verify the one-line conclusion. All values are fixed-seed teaching simulations.

03 把变化拆成 4 个零件 Break the Change into Four Parts

Value

PART 01

匹配权重 Match weights

Q 与 K 已经决定三条连线的 50% / 30% / 20%。 Q and K already set the three lines to 50% / 30% / 20%.

PART 02

Value 内容 Value content

每个候选携带自己的内容方向；滑块只改中间 V。 Each candidate carries a content direction; the slider changes only the middle V.

PART 03

加权贡献 Weighted contribution

每个 V 先乘固定权重，再送到聚合点。 Each V is multiplied by its fixed weight before reaching the gather point.

PART 04

聚合结果 Aggregate

三个贡献相加，形成当前位置真正拿到的内容表示。 The three contributions add into the content representation received by the current position.

04 最小机制：先匹配，再按同一权重取内容 Minimal Mechanism: Match First, Then Gather Content

Value

Attention(Q,K,V) = Σ_i α_iV_i

α 只由 Q/K 匹配得出。拖动 V 不会重算 α，却会改变加权和。 α comes only from Q/K matching. Moving V does not recompute α, but it does change the weighted sum.

固定 Q/K Fix Q/K 连线权重不动 line weights stay fixed

改变 V Change V 内容贡献转向 content contribution turns

重新求和 Sum again 聚合结果改变 aggregate changes

05 边界实验：错误地让 Value 反过来改线宽 Boundary Test: Wrongly Let Value Change Line Width

主动制造失败 Create a failure

把“匹配谁”和“取什么”混成一步 Collapse “who matches” into “what is taken”

点击制造错误耦合：中间 Value 一转，匹配线也随之变粗。对照正常状态，确认这违反 Q/K/V 分工。 Create a wrong coupling: turning the middle Value also thickens its match line. Compare it with the normal state to see why this breaks Q/K/V roles.

尚未执行。先在主交互中观察正常机制。 Not run yet. Observe the normal mechanism in the main interaction first.

✗ Value 决定候选是否匹配。 Value decides whether a candidate matches. → ✓ Q/K 决定匹配，V 提供内容。 Q/K decide the match; V provides content.

✗ 只要线宽不变，聚合结果也不变。 Fixed line widths mean a fixed aggregate. → ✓ 权重不变时，V 内容改变仍会改结果。 Even with fixed weights, changed V content changes the result.

✗ Key 和 Value 只是同一向量的两个名字。 Key and Value are two names for one vector. → ✓ 它们可来自同一 token，却承担不同任务。 They can come from one token while serving different jobs.

06 · 一句话带走 06 · One line to keep

Value 是匹配之后真正被取出的内容；拖动 V 可以检验：Q/K 连线不动，聚合结果仍会改变。 A Value is the content retrieved after matching. Move V to verify that the Q/K lines stay fixed while the aggregate changes.