In this prison discipline case, petitioner was charged with and found guilty of violations of prison disciplinary Rule 1 (OAR 291-40-050(1)) — Disruptive Behavior 1 and Rule 13 (a) (OAR 291-40-050(13)(a)) — Conspiracy to Commit a Rule Violation. 2 We affirm.

This is another of the cases arising out of a concerted work stoppage or sit-down strike which occurred at the Oregon State Penitentiary beginning on February 7, 1979. See Calhoun v. OSP, 41 Or App 339, 597 P2d 1250 (decided this date). As was true in Calhoun, the record here is sparse. It is sufficient, however, to establish that petitioner was an actual participant in the work stoppage in the prison laundry on the day in question. Accordingly, his conviction for violation of Rule 1 is affirmed. See Calhoun v. OSP, supra.

Respondent argues, and we agree, that — at least under the circumstances of this case — the disciplinary committee was entitled to find petitioner’s public joining of the strike constituted "conspiracy” as that term is defined in Rule 13 (a), viz., "* * * an agreement with any other person(s) to * * * engage in or cause rule violations.” The joint action of petitioner and the others permits the reasonable inference of an actual, even if unspoken, agreement to stop work at the prison.

Petitioner relies on Robertson v. OSP, 35 Or App 591, 582 P2d 32 (1978), but that case will not aid him. *352 Robertson involved a discussion of a possible sit-down strike between inmates. The discussion never resulted in any agreement. Here, by contrast, there was a strike. Strikes are concerted actions; agreement lies at their heart. The committee was entitled to view petitioner’s act of joining the strike as a manifestation of an agreement.

Affirmed.