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Walker is facing a two-match ban for simulation following the penalty he was awarded and converted against Celtic.
Visiting captain Scott Brown called Walker "a cheat" after Sunday's match at Tynecastle, with Celtic manager Brendan Rodgers saying referee John Beaton had admitted he made a mistake.
Hearts will make their case for Walker at a Scottish FA judicial panel hearing set for Thursday.
Walker, 23, is now free to play in Wednesday's League Cup visit to St Johnstone.
He scored from the spot to draw Hearts level in the first half before Celtic won the game with a late winner from Scott Sinclair.
Hearts head coach Robbie Neilson said on Tuesday morning that he was disappointed by Brown's "cheat" comment.
"I don't think you should be saying that about fellow professionals," Neilson told BBC Scotland.
"If you have got an opinion on anything you are better just keeping it to yourself."
Neilson did speak to Brown at full time but the penalty incident was not discussed.
"I spoke with Scott after the game but just about coaching as he is doing some coaching with the under 20s.
"What happens on the football park happens on the football park. We move on, he is a good guy and he speaks well and he is into his coaching so there are no issues there at all."
"Disciplinary Rule 201 - At the above match you committed an act of simulation in that you did pretend that you were fouled by a player on the opposing team, namely Kieran Tierney, and did thereafter dive in the penalty box of the opposing team. That this act of simulation caused a match official to make an incorrect decision, namely the incorrect awarding of a penalty to Heart of Midlothian FC."

The man cycled towards the girl in Enfield saying she had been caught shoplifting and he would search her. As he did so, he raped her and threatened her with a knife, the Met Police said.
A 32-year-old man has been arrested.
The attack in Sandhurst Road at 17:30 GMT on Wednesday has been linked to an earlier incident with a 12-year-old.
The 12-year-old girl was approached by a man on a bike on Shirley Grove, near Sandhurst Road, at about 16:30 on the same day.
He told the girl he was a police officer and that she fitted the description of a girl he needed to arrest.
He told her she needed to go to a van with him and when she refused he grabbed her by the wrists. He eventually let go and she managed to run off.
The arrested man remains in custody.
Det Insp Tracey Cormack urged anyone who "may have witnessed these offences or think they may have been approached by this man" to contact the police.

The 81-year-old driver of a Fiesta suffered multiple injuries in the crash on the A4064 between Llangeinor and Brynmenyn on Saturday at 15:05 BST.
He is being treated at Cardiff's University Hospital of Wales. His 75-year-old passenger also needed hospital treatment for head injuries.
The Vauxhall Astra driver was taken to Princess of Wales Hospital, Bridgend.
He has been arrested on suspicion of causing serious injury by dangerous driving.
Police are appealing for witnesses.
Hearts are to contest a diving charge against winger Jamie Walker.
[NEXT_CONCEPT]
A man claiming to be a police officer raped a teenager at knifepoint after stopping her on a street in north London and accusing her of shoplifting.
[NEXT_CONCEPT]
A 24-year-old driver has been arrested after a crash which left two other men hurt, one seriously, in Bridgend.