NEZ is a function of missile speed and remaining energy and the distance to target. This changes throughout the course of flight.
Show me mathematically how ramjet is always better than rocket for greater NEZ.
Ramjet sustains a speed better. The pulsed rocket method allows slow down to around mach 2 or even lower before second boost kicks again. It is highly complex but the way we can determine it is based on how much potential energy is in the rocket powered missile. Overall NEZ is mostly the potential energy but has impact of factors such as lift, thrust to weight, drag, and external factors such as new interception point changes but this last factor we assume as same conditions for both assessment.
So I said before it is impossible to say which has better NEZ. Ramjet doesn't automatically equal better NEZ because sustained mach 3 flight let's say during a period of time when rocket missile is only mach 2, does not give ramjet missile more NEZ since the rocket one will soon be boosted again to mach 4.
I actually provided everything you needed to understand this, but you have got this messed up in your mind. No Escape Zone is the range from which target cannot escape with close to 100% probability, even if the target utilizes escape maneuvers. This happens because the missile is much more faster, and much more maneuverable. But, the missile is also an aircraft and subject to the lift/drag/thrust/weight relationship. Every time the missile is not producing thrust, drag is slowing it down and weight is drawing it down.
Given this, the standard escape maneuver against dual-pulse is to retain altitude superiority. The missile needs a terminal altitude gain to reach the target. In order to do this with near 100% probability, it must be near the target, otherwise it will have lost too much altitude. This reduces the No Escape Zone. The target can make this even worse for the missile by initially lowering altitude, making the missile follow suit and then quickly increasing altitude. The missile needs to be very close to the target so the target has no room for playing around with altitude. The No Escape Zone has been reduced. Also, without thrust, the missile cannot make any high G maneuvers.
The ramjet by definition works in the high supersonic/near hypersonic regime and achieves a thrust by managing the supersonic flow for combustion. Its boost phase is meant to push it into supersonic speed from where the ramjet engine ensures thrust. The ramjet engine cannot achieve supersonic speed on its own, rather, it is designed to retain supersonic speed. Thus, by definition, it will retain a high speed throughout flight path, which will provide it with enough lift and will overcome drag, thus the standard maneuver of retaining altitude is ineffective (within the altitude range where air density make ramjet feasible). This automatically increases its No Escape Zone. If the aircraft lowers its altitude, the missile can use gravity to retain speed and reduce fuel burn. If the aircraft increases altitude the missile will burn slightly more fuel. But there will be a range within which no amount of maneuvering will knock the missile off the tail. Because the missile has the luxury of continuously burning fuel, it will retain its energy superiority for a longer range. This increases the NEZ.
If you want something more concrete than this, you should go and write your own simulation, where you simulate the missile's control algorithm and the aircraft's maneuvers.