# Define what a tie means before comparing rolls

**Part F · L24 · Prerequisite: L23 · One modelling idea**

## Situation, question, and prediction

A Fate Core overcome action faces active opposition from another character with equal skill. Compare their independent 4dF rolls. Predict whether strict wins and strict losses are equally likely, and whether a tie is failure.

## Build

`joint_classify(left, right, scale, function)` calls the function with one value from each distribution. Subtracting the actual callback values gives their shared margin. For an overcome action, a tie attains the goal at a minor cost; a positive margin succeeds, and margin 3+ succeeds with style.

```dice
f = die_faces([-1, 0, 1])
roll = f + f + f + f
bands = scale().step("Below opposition").step("Tie: minor cost").step("Succeed").step("With style")
def compare(left, right):
    margin = left - right
    if margin < 0:
        return "Below opposition"
    if margin == 0:
        return "Tie: minor cost"
    if margin >= 3:
        return "With style"
    return "Succeed"
result = joint_classify(roll, roll, bands, compare)
output("Equal-skill overcome action", result)
output("Tie", result.pmf("Tie: minor cost"))
output("Strictly beat opposition", result.p_at_least("Succeed"))
```

## Run, read, and check

Tie probability is 1107/6561. Strictly beating opposition is 2727/6561, equal to falling below it by symmetry. The denominator is 81×81 sign sequences. A below-opposition result can still lead to success at a serious cost by the game’s rules; this report does not choose that option.

## Change one thing

Add +1 to the first roll only. Strict wins increase; symmetry between win and loss is broken. Ties must still be reported under the same convention.

## Try it yourself

For two opposed d6, build lose/tie/win categories. Answer: 15/36,6/36,15/36. Checkpoint: name the tie rule and explain why both dice are independent, even if both arguments reference one distribution variable.

## Rules and model notes

[Fate Core SRD, dice and the ladder](https://fate-srd.com/fate-core/taking-action-dice-ladder). Four independent Fate dice; their faces are equally weighted −1, 0, +1. Other Fate/Fudge variants are not implied. [Four Actions: Overcome](https://fate-srd.com/fate-core/four-actions). Outcome classification only; no invocations, active-defender resources, or choice of serious cost.

## What you now know / where next

Define what a tie means before comparing rolls is the reusable idea. Follow the generated
previous/next links below, or return to the [course index](index.html).
For a complete self-contained application, see [fate-opposition](../cookbook/fate-opposition.html).