\input zb-basic \input zb-ioport \iteman{io-port 06052615} \itemau{Horv\'ath, Tam\'as L.; Izs\'ak, Ferenc} \itemti{Implicit a posteriori error estimation using patch recovery techniques.} \itemso{Cent. Eur. J. Math. 10, No. 1, 55-72 (2012).} \itemab The authors propose new implicit a posteriori error estimators for elliptic boundary value problems. Local problems are formulated for the error and the corresponding Neumann type boundary conditions are approximated using a new family of gradient averaging procedures. Convergence analysis is discussed and numerical examples are provided. \itemrv{R\u azvan R\u aducanu (Ia\c si)} \itemcc{} \itemut{implicit a posteriori error estimators; finite element method; gradient recovery; elliptic boundary value problem; convergence; numerical examples} \itemli{doi:10.2478/s11533-011-0119-7} \end