Cambridge's controversial system of proportional representation has with-stood a ballot recount demanded by its chief opponent, the Cambridge Young Democratic Association.

The recount, held yesterday morning in the election commissioner's office, established the margin of victory for the PR system at 502 votes, an increase of 47 over the margin announced after the official tabulation of ballots Nov. 8.

According to Massachusetts law, the PR question cannot be placed on the ballot again for four years, but Lawrence W. Brennan, president of the Young Democrats, said last night that his organization "is considering legislative action to get the law changed."

Opponents of proportional representation will urge several Cambridge legislators to introduce bills calling for a change in the Commonwealth law at the forth-coming session of the General Assembly. All bills for consideration by the 1962 legislative session must be filed before next Wednesday.

Brennan said that the Young Democrats "will decide on a definite strategy by the beginning of the week," and affirmed that the organization has been considering alternative action for some time in case the recount of PR ballots failed to produce victory.

The 502 vote margin is the narrowest in PR's 20 years as the Cambridge election system, and many opponents of the plan believe that PR will be defeated the next time it is put in a public referendum.

Brennan said that if the legislature does not act to change the State law, the young Democrats may attempt to get the PR question on the ballot next year "by changing parts of the proposal."

The final vote established in the recount is 16,342 in favor of retaining PR and 15,840 opposed; 1021 ballots were left blank.

Next Wednesday the election commission will recount all the ballots cast in the Cambridge school committee election. The recount was asked by Cambridge Civic Association candidate Douglas P. Adams '30, who missed a place on the committee by 15 votes.