A grant must at some time have been preceded by a request

In reply to a72:

You need to latch the occurrence of req. Thus,


    bit clk, req, grnt, req_occurred, reset_n;  

    always @(posedge clk) begin
        if($sampled(req))  req_occurred <= 1'b1; // updated with the $sampled( 
        if($sampled(grnt)) req_occurred <= 1'b0;
    end
   
   ap_grant: assert property(@(posedge clk) $rose(grnt) |-> req_occurred);  


Ben Cohen
http://www.systemverilog.us/ ben@systemverilog.us
** SVA Handbook 4th Edition, 2016 ISBN 978-1518681448

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