# I.14.2 (Controlled-controlled-Y)

**URL:** <https://discuss.pennylane.ai/t/i-14-2-controlled-controlled-y/1498>\
**Category:** Codebook\
**Created:** [November 23, 2021, 9:50am UTC](https://discuss.pennylane.ai/t/i-14-2-controlled-controlled-y/1498 "2021-11-23T09:50:09Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![qreg](https://avatars.discourse-cdn.com/v4/letter/q/bbe5ce/32.png) [@qreg](https://discuss.pennylane.ai/u/qreg)\
**Post date:** [November 23, 2021, 9:50am UTC](https://discuss.pennylane.ai/t/i-14-2-controlled-controlled-y/1498/1 "2021-11-23T09:50:09Z")

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Hello. It would appear that S^dagger CCNOT S corresponds to the Pauli Y with two control bits, including the correct phase. However, the grader says that my solution is incorrect. Where am I making the mistake?

![I15](https://canada1.discourse-cdn.com/flex012/uploads/pennylane/original/1X/5d49797e25448ad8f2067f4414747cf76e74f43f.png)

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<div class="post-metadata">

**Author:** ![glassnotes](https://yyz2.discourse-cdn.com/flex012/user_avatar/discuss.pennylane.ai/glassnotes/32/327_2.png) [@glassnotes](https://discuss.pennylane.ai/u/glassnotes)\
**Post date:** [November 23, 2021, 2:55pm UTC](https://discuss.pennylane.ai/t/i-14-2-controlled-controlled-y/1498/2 "2021-11-23T14:55:24Z")

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Hi @qreg, your circuit is actually structurally correct, there is just an issue in how `adjoint` is being invoked. [`qml.adjoint`](https://pennylane.readthedocs.io/en/stable/code/api/pennylane.adjoint.html) is something called a _transform_. There are a number of different types of transforms (you can see plenty of examples [here](https://pennylane.readthedocs.io/en/stable/code/qml_transforms.html), but the core feature is that transforms return _functions_). So when we call

```auto
qml.adjoint(qml.S)

```

what gets returned is a function that computes the adjoint of `S`, and takes the same arguments as `S` (in this case, a wire). However, we still need to call that function and pass those arguments:

```auto
qml.adjoint(qml.S)(wires=2)

```

Hope that helps, please let us know if there’s anything else we can clarify!

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<div class="post-metadata">

**Author:** ![qreg](https://avatars.discourse-cdn.com/v4/letter/q/bbe5ce/32.png) [@qreg](https://discuss.pennylane.ai/u/qreg)\
**Post date:** [November 24, 2021, 2:30am UTC](https://discuss.pennylane.ai/t/i-14-2-controlled-controlled-y/1498/3 "2021-11-24T02:30:45Z")

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Thank you, it helped.