Mentor 的文檔說的比較清楚
Example 2-7 defines two cut points (p and q) in order to explore a hard-to-prove assertion
(assert property (r_eq_s)) by reducing the problem to one that can be analyzed successfully.
The variables p and q are large arithmetic expressions, which are typically hard to analyze.
Suppose heuristic knowledge indicates p must be 3, 4 or 5. Then, by adding an assumption for this (i.e., assume property (values_of_p)), the assertion can be proven.
Example 2-7. User-defined Cut Point dut.v
module dut(clk, rst, a, b, c, d, e, f);
input clk, rst;
input [31:0] a,b,c,d,e,f;
wire [31:0] p,q,r,s;
assign p = a * b + (c - d) * (b - f) * (e*f);
assign q = d + e + f + e*e + f*f + a*a;
assign r = (p + 1) + (q - 1) + p;
assign s = 2*p + q;
property r_eq_s;
@(posedge clk) disable iff (rst) r==s;
endproperty
property values_of_p;
@(posedge clk) disable iff (rst) p==3 || p==4 || p==5;
endproperty
assert property (r_eq_s);
assume property (values_of_p);
endmodule