概率分布 · 一整杯怎样分给所有候选Probability Distribution · Split One Whole Across Candidates
non-negative shares + total 1
概率分布是一组候选结果及其概率:每项都不小于 0,全部加起来必须等于
1。它不是三杯各自无限加水,而是把同一整杯在候选之间重分配。A probability distribution pairs candidate outcomes with probabilities. Every share is non-negative and all shares
sum to one. It is one fixed cup being reallocated, not three independent supplies.
01 · 只有一整杯01 · Only one whole cup
如果“猫”的可能性多拿一点,另外两个候选能不能都保持原样?If “cat” receives more probability, can both other candidates stay unchanged?
1.0
02三杯概率水Three Cups of Probability Water
守恒重分配型Conserved reallocation
三杯总量Total volume
1.000
始终守恒always conserved
最大候选Largest candidate
—
当前最高杯highest cup now
最近操作Last changed
—
获得指定份额received requested share
检验方法:记住两只杯子的高度,再把第三杯调高。至少一杯必须下降,总量仍显示
1.000。Verification: note two cup levels, then raise the third. At least one other cup must fall while the total
still reads 1.000.
03一份分布的 3 个条件Three Conditions of a Distribution
候选 + 份额Candidates + shares
PART 01
候选集合Candidate set
猫、狗、鸟是这次互斥的所有候选结果。Cat, dog, and bird are all mutually exclusive outcomes here.
PART 02
非负份额Non-negative shares
每只杯子的水位只能在 0 与 1 之间。Every cup level stays between zero and one.
PART 03
总量为 1Total equals one
三杯共同瓜分完整的可能性总量。The three cups divide the whole amount of possibility.
CHECK
此消彼长Trade-off
一杯上升时,其他杯必须让出同样总量。When one rises, the others must give up the same total.
04最小机制:所有候选共同分 1Minimal Mechanism: All Candidates Share One
Σ pi = 1
pcat + pdog + pbird = 1
上方每次滑动后都重算另外两杯,使 pi ≥ 0 且总和精确回到 1。Every slider move recalculates the other two cups so each pi stays non-negative and the total
returns exactly to one.
提高一杯Raise one cup指定新的概率份额Set a new share
挤压其余杯Compress the others按原比例让出水量Give up water proportionally
总量守恒Conserve total重新相加仍为 1The sum remains one
05边界实验:检验一组伪概率Boundary Test: Inspect a Fake Distribution
主动制造失败Create a failure
声称 0.7 + 0.6 + 0.4Claim 0.7 + 0.6 + 0.4
三项都在 0 到 1 之间还不够;如果总和不是
1,它就不是完整概率分布。主实验的三杯不会被破坏。Keeping each item between zero and one is not enough. If the sum is not one, it is not a complete
distribution. The three main cups remain conserved.
尚未执行。检查非负,也要检查总和。Not run yet. Check non-negativity and the total.
✗ 每项小于 1 就是概率分布。Values below one automatically form a distribution.
→ ✓ 还必须非负且全部加总为 1。They must also be non-negative and sum to one.
✗ 提高一个候选不会影响其他候选。Raising one candidate leaves all others unchanged.
→ ✓ 总量固定,提高一项必挤压其余项。With a fixed total, raising one must compress others.
✗ 最高概率就是必然发生。The largest probability is certain to occur.
→ ✓ 最高只表示在当前候选中占比最大。Largest means only the biggest share among candidates.
06 · 一句话带走06 · One line to keep
概率分布把总量 1
分给所有候选,每项非负;调高任意一杯,就能检验其他杯必然让位而总量仍守恒。A probability distribution assigns a non-negative share of one to every candidate. Raise any cup to verify that
the others give way while the total stays conserved.